Shu Kurenai

is the deuteragonist of the anime and manga series, Beyblade Burst. He currently battles with his beyblade, Spryzen Requiem S3 0 Zeta. Shu is also one of the Supreme Four. In Beyblade Burst Evolution, he joined the American team, the Raging Bulls, to battle in the World Championships, and later secretly became Red Eye, a major antagonist. For a while, he became possessed by his bey Spryzen, but was eventually saved by his best friend, Valt Aoi. He is the Runner-Up of God Blader's Cup.

Appearance
Shu is quite tall for his age and has shaggy white hair and blood red eyes. His attire includes a pink dress shirt with a red striped black tie, a black high-collared vest with a white interior, long black pants, and black shoes. His vest bears a red Beyblade symbol on the left side. His right hand sports a red fingerless glove with yellow accents and a square cuff. He has a scar over his right eye, inflicted by Lui Shirasagi 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.

As Red Eye
As Red Eye, he wore a dark grey-and-red streaked mask that only showed his eyes and mouth. He wore a long white coat 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, implying that his mask had a voice-altering feature. In a later episode, 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 Evolution season finale.

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; 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. This caused some friction between him and Valt, who out of concern for his friend, suggested that he forfeit their battle.

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 Shirasagi breaking his Storm Spryzen in Beyblade Burst, and then later losing to Free de la Hoya, the strongest blader in the world after joining 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 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 Alcacer, 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 S3, 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 S3 for the first time, he became overwhelmed by the immense power it contained and ended up 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 God 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.

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.

Beyblades

 * Spryzen Spread Fusion: Shu's primary Beyblade in the Beyblade Burst manga.
 * Spryzen S2 Knuckle Unite: Shu's primary Beyblade in the Beyblade Burst anime.
 * Legend Spryzen S3 7 Merge: Shu's primary Beyblade in the Beyblade Burst Evolution anime as Red Eye.
 * Spryzen Requiem S3 0 Zeta: Shu's final form of his Beyblade in the Beyblade Burst Evolution anime.

Special Moves

 * Counter Break: Spryzen utilizes its Unite tip to quickly change its trajectory and slam into the opponent at high speeds. This is Shu's most commonly used technique.
 * 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 Slash: When Spryzen is in left spin and the Zeta tip is in attack mode, Shu calls out the move it will deal a finishing blow.
 * Requiem Spin: Spryzen absorbs the opponent's strength and turns it into its own power thanks to the rubber on its Energy Layer. This move is similar to Free's Drain Spin.

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 looks out for him. 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, when he became Red Eye, Shu seemingly abandoned their friendship to create Spryzen Requiem S3. 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.

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.

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 blader's 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 Shirasagi
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 God Bladers Cup, as well as destroying 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.

Boa Alcacer
Shu (as Red Eye) met Boa and encouraged him to not give up in his beytraining. 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.

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

Fubuki Sumie
Shu met a young Fubuki some time after the God 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 to.

Quotes

 * "I'm not really a 'club joining' kind of guy."
 * "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."
 * "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!"
 * "What are you? A mindreader?”
 * "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.
 * "I'm sorry. I know I broke our pact. Some day, I'll make it up to you..."
 * "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."
 * "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!"
 * "Shu as you know him is gone!" - talking to Valt as Red Eye.
 * "I am... Spryzen!" - talking to Valt when possessed by Spryzen.
 * "(screams) VALT!!!!!!"

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.
 * Like other characters in the Burst cast, Shu's family name contains a color. "Kurenai" means "crimson".
 * He is similar to Toby, in the sense that both are best friends of 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 Metal Saga.
 * Whenever Shu wins a battle, he pushes his hair back with his hand to reveal his scar. As episode 14 of Burst shows, he did this even before he had it. However, he stops doing this after adopting the Red Eye alter-ego.
 * Shu is similar to Hiro Granger and Ryo Hagane from the previous series. They all have masked alter-egos that are involved with Beyblade; and also have some sort of relationship with the protagonists.
 * He was the first blader of the series that was able to defeat Lui in the manga.
 * In episode 49 of Evolution, Shu destroys Nightmare Luinor, much like how Lui broke Spryzen the first time Shu lost in the 49th episode of season 1.