Shu Kurenai

is the deuteragonist of the anime and manga series, Beyblade Burst. He currently battles with his Beyblade, World Spriggan Unite' 2B. In addition, Shu is one of the Supreme Four being the runner-up of previous year's National Tournament and a member of the Big Five. In Beyblade Burst Evolution, he joined the American team, the Raging Bulls, to battle in the World Championships, later secretly becoming Red Eye, a major antagonist. For a while, he became possessed by his Bey, but was eventually saved by his best friend, Valt Aoi. He is the runner-up of the International Blader's Cup.

In Beyblade Burst Turbo, he is now the current owner of the Raging Bulls.

Appearance
Shu is quite tall for his age, with shaggy white hair and bright crimson eyes. He also has a scar over his right eye, inflicted by Lui Shirosagi in a previous battle, but it is usually covered by his hair, and therefore unseen until he lifts his hair when he wins a battle.

In Burst, his attire consists of a short-sleeved pink dress shirt with a black and red striped tie, a black high-collared vest with a white interior, long black pants, and shining black shoes; his vest bears a red Beyblade symbol on the left side. On his right hand, he sports a red fingerless glove with yellow accents and a square cuff.

In Evolution, his Red Eye attire consisted of a dark grey-and-red streaked mask that only showed his eyes and mouth. He wore a long white sleeveless tailcoat with a high collar and red accents, a black and red bodysuit underneath, and a matching gauntlet on his left arm. Upon donning the mask, his voice became noticeably deeper than before, though it is unknown if the mask had a voice-altering feature, or if he was disguising his voice by speaking in a deeper range.

In Episode 36, his mask broke during a battle with Lui, revealing his identity to everyone. Shu's hair was also noticeably longer, especially when he was Red Eye, suggesting that it grew longer during his time in the Snake Pit. He later has it cut back to its original length in the season finale.

In Turbo, Shu wears a long-sleeve pink dress shirt, a closed white vest with yellow borders, a black trench coat with crimson borders, navy pants, and white boots with red lines. He also sports his signature red glove. His hair has grown longer as well.

In Surge, Shu retains his pink dress shirt and black tie from Turbo, a white vest, black pants with a thin white stripe on each leg, a pink belt with a black stripe at the center and a gold buckle, white boots with dark-red lines, a black high-collared vest similar to his first one, and he re-dons his square-cuffed red glove. In addition, he has cut his hair short again, closer to his original hairstyle in Burst, save for the right side to conceal his scar.

When he was younger, he wore a white collar shirt under a red vest, black shorts, and brown strap shoes. While training, he sometimes wears a light gray shirt with a red/gray hoodie with black accents; he also wears black shorts & white shoes. While training, he wears a workout attire different from his previous one: a black T-shirt with a blue hoodie that has a Beyblade symbol on the left and and red accents paired with shorts that have red stripes He also wears black leggings underneath.

Personality
Described as a genius blader, Shu is a favorite in his hometown. However, he does not rely on talent alone and is very hardworking when it comes to Beyblade. He is one of the best bladers to ever play the sport, managing to surpass Valt Aoi and win his first WBBA tournament in less than a year.

Shu is calm and patient, and prefers to be alone most of the time. He maintains a cool exterior in front of others, however underneath this lies a burning hot fighting spirit. He is quite standoffish towards people he doesn't know well, with Valt and Xander Shakadera being exceptions. Because of this, he is sometimes seen as aloof and even as a 'spoiled brat', as described by Rantaro Kiyama in the first episode of the anime.

However, despite his usual stoic demeanor, Shu cares deeply for his friends, especially Valt (being his best friend); and will always help them out or give advice to them when they need it.

In the anime, Shu is shown to be a good cook: this is because his parents are often busy and away from home, so he has to take care of himself.

Shu has also demonstrated keen observation skills, such as when he noticed Daigo's guilt in cheating against Yugo, visualizing his opponent's Beys in the stadium while training, and seeing Rantaro finish first when he saw the others racing each other.

Shu had a bit of a stubborn streak when dealing with his shoulder injury. Despite strict orders from the doctor to give his body some time to rest and recover, he still insisted on practicing for his upcoming matches and often denied being in pain only to keep his promise to Valt .This caused some friction between him and Valt, who out of concern for his friend, suggested that he forfeit their battle.

Shu has shown several instances of ambidexterity, such as when he switches between launching with his left and right hands or when cooking with both hands simultaneously.

After becoming the owner of the Raging Bulls, he is often referred to as a legendary Blader.

As Red Eye
Shu's personality takes a much darker turn in Beyblade Burst Evolution upon becoming Red Eye. He changes into a quiet yet powerful and ruthless blader who is willing to destroy others' beys to win. This drastic personality change is due to Lui Shirosagi breaking his Storm Spryzen in Beyblade Burst, and then later losing to Free De La Hoya, the strongest blader in the world, after he joined the Raging Bulls, a legendary American team.

This hints that Shu may have perfectionist habits, as he seemingly punishes himself for losing. His transformation is completed when he joins the Snake Pit Organization, led by the mysterious Ashtem, and he cuts himself off from his friends.

As his alter-ego, Shu seeks out those who pose a challenge to defeat, scouting the globe for particularly strong bladers. This is an effort to improve his own skills to order defeat Free and Lui one day. However, this leads Shu to push away his friends, most notably Valt, evidenced by him roughly shoving him aside and demanding him to leave after his identity is revealed. This also leads him to believe that strength is more important than anything else, which is the advice he gives Boa Alcazaba, a rookie member of the Snake Pit.

When Shu is put through The Requiem Project, one of the tasks he has to accomplish to receive his new Beyblade, Spryzen Requiem, is to eliminate Valt from his imagination and break their friendship. This shows that Shu still cares about others, but he is being pushed into abandoning the things that made him happy in his old life.

When Shu picked up Spryzen Requiem for the first time, its immense level of power led to him having his psyche being taken over by Spryzen's spirit, to the point where he even stated to be Spryzen on several occasions. While under the effects of Spryzen's power, Shu acts more power-hungry, aggressive, and overall more hostile and ill-tempered; a stark contrast to his usual calm and gentle personality.

It is interesting to note that Shu's personality as Red Eye is eerily similar to that of Lui, with his new desire to seek out opponents he views as worthy to face, and how he is set on defeating all who stand in his way. He also starts to destroy other people's beys, such as when he destroys Ghasem's Maximus Garuda, Norman's Twin Noctemis, the Reboot tip on Valt's Genesis Valtryek, and Lui's Nightmare Luinor. He also tears one of Ken Midori's hand puppets, Besu.

However, during his final match with Valt in the International Blader's Cup, Shu was freed from Spryzen's mind control after Valt defeated him, and thus he became his old friendly self once again and reconciled with Valt and the rest of his friends.

Turbo
In Beyblade Burst Turbo, due to his past experiences in the previous seasons, Shu has become wiser and more empathetic, as he mentions to Fubuki that he, like him, used to care only about practicing Beyblade. He also attempts to relate to Aiger, whose resonance with Z Achilles was becoming corrupt, by pointing out that he had let his obsession with winning consume him as well.

Beyblade Burst (anime)
Shu was introduced in Lets Go! Valtryek!, where he is first seen on a TV broadcast on Beyblade. He is introduced as one of the strongest Bladers around, and easily defeats his opponent with a single hit. During his journey home, he sees Valt training and questions what he is doing, to which he smiles and encourages him to continue. During Valt's first round match in the local tournament, he is shocked when Valt performs a Rush Launch.

In Episode 2, he is later seen in the terrace of his school practicing; his practice is interrupted by Rantaro and Valt's argument.

In episode 10, he is seen practicing when Nika and Toko notices him. When they were running towards him, Nika trips over him and, due to trying to dodge that, he injures his shoulder. He later visits the doctor's office where he is told to stop beyblading to recover. The next day, Shu is seen at school having a battle with Valt where he wins the battle by using Counter Break.

In Episode 11, Shu is at the clinic and his injury is getting even worse due to the battle he had yesterday. Nika calls out for Shu to which he doesn't reply. Nika then tells Valt everything what happened at the park and he rushes in search for Shu.

In Episode 49, he loses to Lui Shirosagi in the semifinals of the National Tournament, breaking his pact to Valt Aoi made in Episode 01.

Beyblade Burst Evolution
Shu is scouted by and joins the Raging Bulls, which allows him to become much stronger than he already is. However, he later lost the No. 1 Blader in the world, Free De La Hoya. This, coupled with his lingering bitterness over his loss to Lui and shame over breaking his promise to Valt, led to him being coaxed by Ashtem into joining the Snake Pit, where power soon corrupted him, turning him into Red Eye, a ruthless Beyblader with a lust for victory and no sense of honor.

After losing to Lui once again, Shu abandons his Evolution Beyblade in favor of creating a new one. He ends up getting possessed by his new Beyblade. By the International Blader's Cup, Shu makes it to the finals with Valt, giving him a chance to rectify his broken promise from the previous season. In the end, Valt ends up victorious and Shu is saved from his Beyblade's control on him.

Beyblade Burst Turbo
Shu made a few appearances in flashbacks throughout the early episodes of the season. He was revealed to have become a mentor to Fubuki Sumiye, evidenced by the latter taking after his launching stance and strong desire for practice and hard work. It was also revealed that at some point during the two-year timeskip, he had gone back to America and became the new owner of the Raging Bulls, succeeding Theodore Glass.

He officially appeared in Episode 12, having a conversation with Fubuki via cellphone. After Fubuki confided in him about his loss in the Luinor Cup, Shu simply advised him to not give up and convinced him to leave Japan for America. There, he aided in Fubuki's training by giving him some helpful pointers on launching, while also showing him that Beyblade should be fun and not just about practice and hard work. It was also mentioned that he explained to Fubuki about Bey resonance.

Later on, Shu is made aware of Aiger Akabane's possessed behavior and growing obsession with power and, along with Fubuki, sets off to confront him at the mysterious castle known as Dread Tower. Once there, he challenged Aiger to a battle with his new Turbo Spryzen, which he won with ease. He then attempted to explain to Aiger that his resonance with Achilles was corrupted and that he was hurting his Bey by forcing his will upon it. Unfortunately, Aiger refused to believe this. Aiger is later purged of his dark power during a battle with Phi, but at the cost of his Z Achilles being destroyed. Taking pity on Aiger, Shu accompanies him to Japan, where he helps him rebuild his Bey, as well as teaching him how to properly resonate with his new Turbo Achilles.

After witnessing the destruction of Free’s Geist Fafnir at the hands of Phi, he is seen running on a treadmill, preparing for if/when Phi targets him next.

Later on, Phi approaches Shu in Central Park and challenges him to a battle. Shu is then seen training with some Beylaunching AI’s, all of which he easily defeats.

In Episodes 46-47, Shu and Phi have their battle, and while the former takes an early lead, Phi proves to be too powerful and shatters Turbo Spryzen.

In the next Episode 48, he is seen along with Ranjiro, Fubuki, and Suoh helping Aiger train for his upcoming match with Phi. In addition, he is shown to have gotten Turbo Spryzen fixed following its previous destruction.

Beyblade Burst Rise
Shu briefly appears in a vision in Episode 15 when Aiger is explaining to Dante how he became the Blader he is in the present day.

Beyblades

 * Spryzen Spread Fusion: Shu's primary Beyblade in the Beyblade Burst manga.
 * Storm Spryzen Knuckle Unite: Shu's primary Beyblade in the Beyblade Burst anime.
 * Legend Spryzen 7 Merge: Shu's primary Beyblade in the Beyblade Burst Evolution anime as Red Eye until he abandoned it for Spryzen Requiem.
 * Spryzen Requiem 0 Zeta: Shu's final form of his Beyblade and former host in the Beyblade Burst Evolution anime.
 * Turbo Spryzen 0Wall Zeta' : Shu's new Beyblade in the Beyblade Burst Turbo anime. It was destroyed by Phi in Turbo episode 47, but was repaired in the very next episode.
 * World Spriggan Unite' 2B: Shu's new Beyblade in the Beyblade Burst Surge anime.

Special Moves

 * Counter Break: Spryzen utilizes its Unite or Merge Performance Tip to quickly change its trajectory and slam into the opponent at high speeds. This is Shu's most commonly used technique in the series.
 * Upper Launch: Shu launches Spryzen at a steep angle, allowing it to attack the opponent from below, or Spryzen uses the stadium's slope to send the opposing bey flying.
 * Ultra Counter Break: A stronger version of the Counter Break in which Spryzen rides along the stadium's groove to pick up speed and deal heavy damage, similar to Valt's Ultra Flash Launch.
 * Ultra Upper Launch: Shu launches Spryzen at an even steeper angle allowing it to gain even more speed and power.
 * Crux Boost: Shu holds his launcher vertically with his right hand, and when he is about to launch he rapidly switches to a horizontal launch. When launched, Spryzen moves around at a very high speed and with great stability.
 * Axe Launch: Legend Spryzen grinds on the stadium floor gaining speed and power, then changes its trajectory to attack the opponent.
 * Requiem Whip: When Spryzen is in Counterclockwise Attack Mode, it uses its metal axe to hit the opponent with a strong attack.
 * Requiem Spin: In Counterclockwise Stamina Mode, Spryzen absorbs the opponent's strength and turns it into its own power thanks to the rubber on its Energy Layer. It can also be utilized in Clockwise Stamina Mode against left-spin opponents. This move is similar to Free's Drain Spin.
 * Turbo Awakening:When Shu is in sync with Turbo Spryzen, the Turbo Blades activate, giving Spryzen more attack power. This also triggers burst stoppers which, as the name implies, prevent the bey from bursting when active.
 * Turbo Crux Boost: Shu holds his launcher vertically behind his back, then jumps forward, thrusts his launcher in front of him, and quickly switches his launcher to a horizontal position. This gives Spryzen a lot of speed and power as well as unlocking the Turbo awakening.
 * Turbo Counter Break: Using the flat edge of the Zeta' tip’s Stamina setting, Turbo Spryzen changes its trajectory and gains speed for a powerful counterattack.
 * Turbo Upper Launch: In Counterclockwise mode, Turbo Spryzen uses the Zeta' Performance Tip to change its spin direction temporarily while gaining speed and power to hit the opponent with a massive attack.
 * Turbo Spryzen Whip: Turbo Spryzen channels its energy into the Turbo blades to slash the opponent with a sharp edge for massive attack damage.
 * Sparking Shoot:
 * World Spin:

Beyblade Burst
Shu is Valt’s best friend, and he is considered to be a Beyblade prodigy, being one of the four finalists from the last National Tournament. Cool, calm, and collected, Shu works extremely hard to be the best Blader he can be. His relationship with Valt, a unique combination of friendship and rivalry, motivates them both to continuously improve and grow together.

As Red Eye
The most powerful Blader of the mysterious organization known as Snake Pit, Red Eye is never seen without his mask, making his true identity a secret. He will take down anyone he sees as a threat to his ultimate goal of being the strongest Blader in the world.

As Shu Kurenai
Shu Kurenai is the true face behind the Red Eye mask. After losing to Lui Shirosagi, Shu returned to the Snake Pit in order to push himself to new physical and mental limits.

Discarding Legend Spryzen, Shu underwent the trials of the Requiem Project. There, Spryzen Requiem was born. Now, Shu has forsaken his past and seeks only power.

Beyblade Burst Turbo
Having discarded the mantle of Red Eye and reclaimed his true self, legendary Blader Shu Kurenai now acts as leader and mentor of the Raging Bulls. Sensing the changes coming to the Blading world, he creates Turbo Spryzen as a mean to stay ahead of the competition.

Beyblade Burst

 * Episode 01 - Let's Go! Valtryek!
 * Episode 02 - Kerbeus: Guard Dog of The Underworld!
 * Episode 03 - Blast-Off! Rush Launch!
 * Episode 04 - Beyblade Club: Let's Get Started!
 * Episode 05 - Into the Darkness! Dark Doomscizor!
 * Episode 06 - Get Ready! Crash Course!
 * Episode 07 - The Flash Launch! It's Crazy Fast!
 * Episode 08 - A Powerful Opponent! Hyper Horusood!
 * Episode 09 - Wyvron in the Way!
 * Episode 10 - Get Over It! Trust in Valtryek!
 * Episode 11 - Spryzen's Despair!
 * Episode 12 - Shield Crash Menace!
 * Episode 13 - Shu's Test!
 * Episode 14 - The Battle We Promised!
 * Episode 15 - A Fierce Battle! Valtryek Versus Spryzen!
 * Episode 16 - A Group Lesson! Shakadera Special!
 * Episode 17 - Extreme Xcalius!
 * Episode 18 - Team Battle! It's Off the Hook!
 * Episode 19 - Roktavor vs Unicrest!
 * Episode 20 - Bring it Together! Chain Launch!
 * Episode 21 - A Battle of Friendship!
 * Episode 22 - Valtryek Awakens!
 * Episode 23 - Lonely Doomscizor!
 * Episode 24 - Full Strength, for Real!
 * Episode 25 - The Mysterious Masked Blader!
 * Episode 26 - Let's Do This Thing!
 * Episode 27 - Training Camp! The Biting Stadium!
 * Episode 28 - Mountains! Rivers! A Huge Stormy Adventure!
 * Episode 29 - Eye On The Prize!
 * Episode 30 - The Winged Snake! Quetziko!
 * Episode 31 - Teachings of a Legend!
 * Episode 32 - Cyclone Power!
 * Episode 33 - Mega Flames! Dual Sabers!
 * Episode 34 - The Beasts Bare Their Fangs!
 * Episode 35 - Primal Attack! Beast Betromoth!
 * Episode 36 - Rideout Rising!
 * Episode 37 - Next Stop, Team Finals!
 * Episode 38 - Battle to the Finish! Lost Luinor!
 * Episode 39 - Into the Vortex! Lost Spiral!
 * Episode 40 - All In! Going Solo!
 * Episode 41 - Nepstrius' Trap!
 * Episode 42 - Jumbo Jormuntor! The Venomous Snake!
 * Episode 43 - Winged Launch!
 * Episode 44 - Roar! Battle of the Beasts!
 * Episode 45 - Spryzen vs Wyvron!
 * Episode 46 - Battle for the Top! Valt vs Xander!
 * Episode 47 - Star Battle!
 * Episode 48 - Semi-Finals! Spin Versus Speed!
 * Episode 49 - Old Rivals! Lui Versus Shu!
 * Episode 50 - Overthrowing The King!
 * Episode 51 - Final Showdown! Victory Valtryek!

Beyblade Burst Evolution

 * Episode 04 - Whirlwind! Tempest Wyvron! (flashback)
 * Episode 08 - Season Opener! European League! (flashback)
 * Episode 09 - Alter Cognite! The Shape Shifter! (flashback)
 * Episode 10 - Free to Launch! (flashback)
 * Episode 11 - BC Sol! A Team Divided!
 * Episode 13 - Twin Scythes! Double Strike! (flashback)
 * Episode 15 - Ghasem! The Airborne Blader! (flashback)
 * Episode 16 - The Search For Shu! (as Red Eye)
 * Episode 17 - Shadow Magic! The Snake Pit! (as Red Eye)
 * Episode 18 - The Underground Maze! (as Red Eye)
 * Episode 19 - Secret Fire! Red Eye! (as Red Eye)
 * Episode 24 - World League! Setting the Stage! (as Red Eye)
 * Episode 27 - Worlds Collide! Home Turf! (as Red Eye)
 * Episode 28 - Vampire! Deep Caynox! (as Red Eye)
 * Episode 33 - The World League Final! (as Red Eye)
 * Episode 34 - Full Power! Spring Attack! (as Red Eye)
 * Episode 35 - To The Podium! (as Red Eye)
 * Episode 36 - Lúinor vs. Spryzen!
 * Episode 37 - Challenge of Champions! 
 * Episode 38 - Requiem Project! Spryzen Unleashed!
 * Episode 39 - Emperor of the Underground!
 * Episode 40 - Bow Down! Boom Khalzar!
 * Episode 41 - Colossus Hammer! Twin Noctemis!
 * Episode 42 - BC Sol Scorcher!
 * Episode 43 - White Hot Rivals!
 * Episode 44 - Epic Evolution! Strike Valtreyk!
 * Episode 45 - Spryzen the Destroyer!
 * Episode 46 - No Limits! Free vs. Lui!
 * Episode 47 - Full Force! Charging Up!
 * Episode 48 - Teamwork! To the Semi-Finals!
 * Episode 49 - The Fierce Four!
 * Episode 50 - Breaking Point! Bursting Through!
 * Episode 51 - A Champion is Crowned  

Beyblade Burst Turbo

 * Episode 05 - Turbo Match! Valtryek vs. Lúinor! (flashback)
 * Episode 07 - Curtains Rise! The Lúinor Cup! (flashback)
 * Episode 12 - Bull's-Eye! Archer Hercules!
 * Episode 17 - Sword of The Legendary Hero! (flashback)
 * Episode 20 - Explosive Flames! Revive Phoenix! (flashback)
 * Episode 29 - Dark Prince! Dread Hades! (illusion)
 * Episode 31 - Rebirth! Turbo Valtryek!
 * Episode 32 - Dread Tower! The Dark Citadel!
 * Episode 34 - Secret of The Fused Bey!
 * Episode 35 - Spirit of Flame! Turbo Spryzen!
 * Episode 36 - The Darkness Within!
 * Episode 37 - Turbo Clash! Showdown in The Dark Citadel!
 * Episode 38 - Rebirth! Turbo Achilles!
 * Episode 39 - Aiger's Rematch! Unbreakable Bond!
 * Episode 40 - Master of The Wind! Air Knight! (flashback)
 * Episode 43 - Lord of Destruction! Dread Phoenix!
 * Episode 46 - Take Flight! Aerial Showdown!
 * Episode 47 - Spirit of Flame Vs. Lord of Destruction!
 * Episode 48 - Blading Together! Turbo Awakening!
 * Episode 49 - Aiger Vs. Phi!
 * Episode 50 - Aiger's Turbo Resonance!
 * Episode 51 - Bonding! Aiger Vs. Valt!

Beyblade Burst Rise

 * Episode 15 - Invasion! The New King! (Vision)

Beyblade Burst Surge

 * Episode 04 - Hear the Voice in Your Bey!/Meet the Monster: Free De La Hoya! (Image)
 * Episode 06 - Dream Tag Battle!/Shirasagijo x The Mythological Island of Demons! (Flashback)
 * Episode 07 - Conquer the Demon Dungeon!/Fierce Storm! Rage Longinus!
 * Episode 08 - The Jet Black Sun! Variant Lucifer!/Barrier! Variant Wall!
 * Episode 09 - Heaven!? Hell!!/GT is Here!
 * Episode 11 - The Great Revolution! Legend Festival!/Super Z! Infinite Achilles!
 * Episode 14 - Win and Go Forth, Zoom Zoom Zoom!/Strongest and Unbeatable vs. The New Generation!

Valt Aoi
Valt is Shu's best friend, whom the former idolizes, and the two have known each other since kindergarten. Valt is continually inspired by the hard-work and focus Shu puts into blading, and continually seeks advice from him. Shu tends to drop his cold front in front of Valt and smiles more easily around him. He's also very protective of Valt and constantly looks out for him, with Valt doing the same when necessary, much like when everyone discovered Naoki sabotaged Shu's match in the Individual Tournament. Shu's faith in Valt is unshakable, and while others may become exasperated with Valt's empty-headed antics, Shu never stops believing in him. He views Valt as a worthy opponent and rival.

In Burst Evolution, Shu continues to believe Valt will be a better Blader and still thinks about battling him again someday. However, when he became Red Eye, Shu seemingly abandoned their friendship to create Spryzen Requiem. He later lost to Valt in Evolution during the events of Episode 51. Fortunately, Shu returned to his old self afterwards, allowing him and Valt to mend their broken friendship.

Two years later in Burst Turbo, Valt and Shu's friendship is still strong, though the two have gone their separate ways (Valt traveling the world to defend his World Champion title, and Shu returning to America and becoming the Raging Bulls' new owner). They were eventually reunited when they met up at the castle called Dread Tower. When Shu’s Turbo Spryzen is destroyed by Phi in battle, Valt attempted to avenge his best friend by challenging Phi himself (before ultimately deciding to let Aiger take him on instead), to which Shu was touched by.

Toko Aoi and Nika Aoi
Because they are Valt's younger siblings, Shu also cares about them. In the Japanese version, both siblings refer to Shu as "Shu-kun" despite being younger than him, indicating that they're quite comfortable with each other.

Daigo Kurogami
Shu and Daigo originally only spoke in passing. Shu was the only one to notice that Daigo cheated during his match with Yugo, and saw how the guilt affected him. He approached Daigo privately and offered some words of comfort, even going out of his way to lie to Daigo's little brother, Ryota, so that the latter wouldn't see his brother in a bad light. This spurred a budding friendship between the two.

In later episodes, Daigo is seen returning the favor by looking out for Shu and worrying about his shoulder injury acting up again. During the International Blader's Cup, he is seen with Ken Midori attempting to bring back the "old Shu" before Red Eye tears Ken's puppet, because of the friendship that spurred a while back.

Xander Shakadera
Like Valt, Shu and Xander are great friends and have been since kindergarten. The two of them have a deep mutual respect for one another and always look out for each other. Shu sees Xander as a trustful friend and worthy rival in terms of Beyblade, given that both are members of the Supreme Four.

Wakiya Murasaki
Shu respects Wakiya as an equal member of the team, and is willing to accept the other Bladers' challenges and intense will to surpass him. Shu can also see past Wakiya's blustering and overly-confident exterior to see that he has insecurities about losing as well, which is why he reminds him that losing a battle isn't the end of the world, and teaches him that it is best to be resilient and persistent.

Lui Shirosagi
Shu and Lui have a shared hatred for one another: While Shu feels the need to avenge his loss at Lui's hand at the last tournament, Lui wishes to crush Shu's dreams and break his spirit. This causes them to fight their hardest against each other. After his previous loss, which left Shu very shaken, he pushes himself to the limit, ignoring Lui's poisonous taunts to beat him in battle.

Even when Shu loses against Lui for the second time and Spryzen is destroyed, he still has the burning desire to win, and promises to never stop trying. This motivation is what cause Shu to become Red Eye in order to defeat Lui and eventually succeeded in defeating him during the semi-finals of the International Blader's Cup, as well as destroying Nightmare Luinor.

Free De La Hoya
Losing against Free after he joined the Raging Bulls made Shu vulnerable to Ashtem's manipulation, allowing Ashtem to turn him into Red Eye. Beforehand, Shu also called out Free for abandoning his previous team, BC Sol. During the International Blader's Cup, Free became interested in battling Shu, but their battle never took place.

Boa Alcazaba
Shu (as Red Eye) met Boa and encouraged him to not give up in his Bey training. He told him that to get stronger he would have to ditch that mindset; that he would never get as good as Red Eye, and try harder. This led to Boa idolizing Red Eye and following him around as he trains to grow stronger than him. A good example is when Shu loses to Lui, Boa was disappointed that someone as strong as him lose and mentions how much he idolizes him.

Shu seems supportive of Boa's training efforts, but can be distant and harsh sometimes.

Theodore Glass
Theodore saw potential in Shu and scouted him to be part of the Raging Bulls. When Shu was depressed after losing to Free De La Hoya, Theodore convinced him to join the Snake Pit to help increase his strength, even creating the ultimate Bey, Spryzen Requiem 0 Zeta, for him. This led to Shu becoming Red Eye, at the cost of losing all his morals. At the end of the season, however, after being brought back to his senses by Valt, Shu later cut all ties with the Snake Pit. In Turbo, Shu later succeeded Theodore as the new owner of the Raging Bulls by going back to America during the two-year time leap.

Norman Tarver
Shu didn't have much of a relationship with Norman, though the latter had a one-sided rivalry with him which stemmed from Shu having stolen his position as the Snake Pit’s strongest Blader. And while Shu seemed unaware of this rivalry, his destruction of Twin Noctemis suggests that he might have seen him as a powerful Blader.

Fubuki Sumiye
Shu met a young Fubuki some time after the International Blader's Cup. Impressed by Shu's skills, Fubuki asked to train with him so he could become a Blader like him one day, to which Shu agreed. The two have since keep in close touch with each other and maintained a strong mentor/student relationship as well. Shu has on several occasions given Fubuki useful advice to help him improve as well as comforting and encouraging him whenever he doubted himself, shown by him convincing Fubuki to leave Japan for America where he taught a deeper meaning of Beyblading to him. His personality has a great influence on his pupil.

Aiger Akabane
Shu rushed to Aiger's rescue in Dread Tower along with Fubuki to prevent him from making the same mistake of getting consumed by his bey by telling about his earlier possession, but it fell on deaf ears as Aiger refused to listen. Later, Shu accompanies Aiger on his way back home where he helps him in recreating his Beyblade while teaching him bey resonance. Aiger later visited Shu with Valt after they came to know about the former's battle with Phi. Shu also helped in Aiger's practice with other Bey Club members for his battle with Phi and later watched his match with Valt.

Quotes

 * "I'm not talking about who got into it first...See you in the finals, then?" -to Valt in the first episode of the series
 * "Brain freeze. It's a thing." - to Valt.
 * "I'm not really a 'club joining' kind of guy."
 * "I think that launch failed because my hand was moving. One more time! I need the practice!" - in a flashback, during his first Beybattle with Valt shortly after getting Storm Spryzen
 * "You know he can't hear you, right? This is how Valt is; he loses his cool."
 * "You're not doing yourself any favors underestimating Valt."
 * "Not cool to smack-talk your own teammates."
 * "Hey! We won as a team!"
 * "We're all bladers here. There's only one way to settle this: with our beys!"
 * "I think I know my own limits, okay? Don't jump to conclusions!"
 * "I am not a fortune teller.” -as Red Eye after being asked if Valt and the others stood a chance at getting to battle him.
 * "Didn't see that coming. Valt, I think you went after the wrong guy." -Shu after Valt knocked him over when they were little in a flashback.
 * "Spryzen...Aw man, I just pushed you way too far...I'm sorry. I let you down..." -holding back tears after Spryzen broke
 * "I'm sorry. I know I broke our pact. Some day, I'll make it up to you..." - apologizing to Valt for breaking his promise.
 * "When I win, I realize how much Beyblade has changed my life for the better."
 * (when the others want Shu to tell them who won the race) "(sighs) It was Rantaro."
 * "I will become a Blader worthy of this Spryzen." - as Red Eye
 * "I failed to take Lui down. Because of that, I couldn't keep my promise to you." - explaining to Valt why he was leaving for America.
 * "You had Valt Aoi on your squad, right? Why would you just abandon them like that?" - Shu asking Free why he left BC Sol.
 * "Don't make me regret letting you in."
 * "Spryzen, Upper Launch!"
 * "Valt, you can beat him."
 * "That's not even a question.." -in a flashback after Theodore asked him if he wanted to become stronger, following his loss to Free.
 * "Shu as you know him is gone!" - talking to Valt as Red Eye.
 * "No Bey can defeat me, I'll crush all of them." - as Red Eye.
 * "You, get out of my way!" - to Valt after his identity is revealed.
 * "Like I already told you, Shu Kurenai is long gone."
 * "Fear me. I will end you."
 * "I'll never forget what you did to me, Lui. You'll regret it soon. First, I'm gonna destroy Nightmare Luinor! Then, I'm gonna annihilate each and every Bey that dares to get in my way!"
 * "Red Eye is no longer here. I'm Spryzen." - to Theodore


 * "I'm done with you. Get out of my way, Valt!"
 * "Give in. You're wasting your time."
 * "You're wrong! I'm Spryzen! Meet your fate!" - talking to Valt while possessed by Spryzen.
 * "(screams) Listen, Valt! I admit it, you're my best friend! It's true! That's why I can't fail! I would never be able to forgive myself if I lost this battle! I won't ever let you defeat me, Valt!"
 * "Hey, listen. I'm proud of you. That was a blast." - after being brought back to his senses.
 * "Hey guys, I'm sorry..." - apologizing to everyone for his behavior as Red Eye and when possessed by Spryzen.
 * "I keep expecting to see you." -thinking about his friends.
 * "Fubuki, do you love blading with all your heart?" -To Fubuki Sumiye when he asked if he could ever become great at Beyblading
 * "I am sorry to hear about the Luinor Cup. Fubuki, stay strong, there is nothing for you to worry about. Just keep moving forward. In fact, get out of Japan and let's catch up."-to Fubuki after his loss in the Luinor cup.
 * "Your resonance is corrupt. In your urgent quest for power, you've resorted to dominating Achilles against its will." -telling Aiger that he is hurting his Bey
 * "Like my Turbo blades?" -During his first battle with Aiger
 * "When I'm fully resonating with Spryzen and I can pull off the optimal launch, its Turbo Blades activate. This is what's known as "Turbo Awakening". When the Turbo Blades activate, Spryzen's power skyrockets to an epic level, and they also serve to protect the Bey. That way, it can't be Burst. However, take it from me that entering the Awakened state isn't the easiest task to accomplish. That's where the bond between you and your Bey comes into play." -explaining how the Turbo Awakening works.
 * "There was a time in the past when I went by the name of Red Eye. I wanted to become stronger, so I just tossed aside the Blader Shu Kurenai. My perception was warped; I thought power came from destroying Beys. In order to become the best, I began trying to control Spryzen, but instead I was swallowed up. If I'd kept going like that, I'm positive that I would've been completely ruined as a Blader. However, I was lucky enough to have a friend. A friend who dragged me out of the darkness and showed me I was wrong. He put every emotion he had right into his Bey, and he used every bit of that strength to show me... exactly what true strength was, and true resonance." - talking about his days as Red Eye and explaining how Valt saved him from his destructive ways."
 * "Don't assume you'll destroy Turbo Spryzen so easily." -accepting Phi's challenge
 * "Don't tell me you really thought I'd be swallowed up by your shadows!" -after resisting Phi's corruption

Gallery
For a full gallery of images of Shu, see Shu Kurenai/Gallery.

Trivia

 * His first name "Shu" means "top class" in Japanese. This may refer to his expert Beyblading skills.
 * His name, Shu, and his bey, Spryzen share the same initials, hinting at the letter S in the centre of his bey.
 * Shu is the first Burst character whose bey was destroyed.
 * Like other characters in the Burst cast, Shu's family name contains a color. "Kurenai" means "crimson".
 * Shu has the same surname as Ren Kurenai from Beyblade: Shogun Steel, but there are no relations between them.
 * He is similar to Toby, in the sense that both are best friends of the protagonists and have been brainwashed into becoming their respective evil alter-egos.
 * Shu's personality shift as Red Eye is similar to Brooklyn's dark side taking him over in the Original series, as well as Ryuga and Tsubasa being taken over by the dark power in the Metal Saga, and Daigo briefly being consumed by evil thoughts in the first season of Beyblade Burst.
 * Shu became possessed by his bey Spryzen, much like how Ryuga was possessed by L-Drago in the beginning of the Metal Saga series.
 * Whenever Shu wins a battle, he is known to push his hair back with his hand to reveal his scar. As episode 14 of Burst shows, he did this even before he had it. And while he stopped doing this during his time as Red Eye, he started doing it again, as seen in his battle with Aiger in episode 35 of Turbo.
 * Shu's scar glows bright red when he experiences intense emotions such as anger, usually when face-to-face with Lui or when he was under Spryzen Requiem's mind control.
 * Shu is similar to Hiro Granger and Ryo Hagane from the previous series. All have masked alter-egos that are involved with Beyblade; in addition to having a relationship with the protagonists. However, Shu has no family relationship to Valt, unlike both Hiro and Ryo.
 * His first beyblade in each season was either broken or abandoned by him.
 * He was the first Blader of the series that was able to defeat Lui in the manga.
 * In Episode 49 of Beyblade Burst Evolution, Shu destroys Lui's Nightmare Luinor, similar to how Lui broke Storm Spryzen in Episode 49 of Beyblade Burst.
 * In the character popularity polls held in Japan in 2018 and in 2020, Shu won 1st place as the most popular Burst character.
 * Shu is one of five characters to use a dual-rotation Bey; the others being Julian Konzern and King from the Metal Saga, and one of three Burst characters, (Count Nightfell and Delta Zakuro), to do so. He is also the first Blader in the Burst series to own a LR launcher.
 * Shu is second Blader to have had his bey destroyed twice. The first being Storm Spryzen which was destroyed in battle with Lui Shirosagi in episode 49 of Beyblade Burst, and the second being Turbo Spryzen which was destroyed at the hands of Phi in episode 47 of Beyblade Burst Turbo. The first was Ghasem Madal with Kerbeus K2 Gravity Revolve and Maximus Garuda.
 * However, he got Turbo Spryzen repaired in Turbo episode 48.
 * Shu was the first of the three characters to get a Turbo Awakening Bey in Beyblade Burst Turbo, the second being Valt Aoi and third being Aiger Akabane.
 * Shu is the only character in Turbo who didn't own a level chip.
 * Shu's zodiac is a Libra.
 * Shu is one of seven characters who did not make an anime debut in Beyblade Burst Rise, but made an appearance in the manga: the six others being Silas Karlisle, Kristina Kuroda, Trad Vasquez, Lui Shirosagi, Rantaro Kiyama, Ken Midori, and Daigo Kurogami.