Kazuma "Kazu" Mikura (Mikura Kazuma 美鞍 数馬), known informally as Kazu, is the second-in-command of team Kogarasumaru and the best friend of the series' protagonist, Itsuki Minami. He lives with his elder sister, as his parents are overseas.
Kazu is a blond-haired, blue-eyed teenager . Specifically, he is 15 (14 at the start of the series), 165 cm tall, weighs 49 kg and is blood type A. His usual attire consists of an off-white beanie, pale blue hoodie pullover [or his black uniform jacket in the beginning], black pants and fingerless gloves; he only takes off his beanie when he gets serious. On occasion, he wears a black jacket with Kogarasumaru's logo emblazoned on the back. His looks and introverted personality have earned him many online fans, who refer to him as "Pegasus descended to Earth". In this description, he is shown as a knight in shining armor riding a white, winged horse.
Kazu was originally bullied by Itsuki Minami as a child, and he often feels like others are more important than himself, especially compared to Ikki's natural talent. Kazu's timid and insecure nature was born from years of living in the shadow of Itsuki Minami, his much more assertive and outgoing best friend. This introverted nature, coupled with a tendency to underperform, often leads others to underestimate him, especially when compared to the brasher personalities of Ikki and Agito. In reality, he is hard-working, smart, and dedicated; of the members of Kogarasumaru, he trains the most and hardest. Kazu is extremely loyal to his friends, and is described as "having the passion to melt all". Although less prone to fits of pervertedness, he does have certain weaknesses which are exploited at several points in the series. He is mostly oblivious to Emily's infatuation with him. Emily's hand was once shown lifted by Kazu to touch the Moon while he explained that, although he does not consider himself as naturally talented or skilled as other Riders (such as Agito or Ikki) he believes that his position and disposition allows him to better understand and strive towards things that other, more gifted people, would not.
In the series' chronology, the earliest appearances of Kazu were in flashbacks, where he was a childhood friend of Ikki. As the more passive of the duo, he was constantly maltreated and bullied by Ikki, who would pull pranks and steal his belongings. Nonetheless, Kazu remains a stalwart companion, and joins the East Side Gunz with him and Onigiri when they enter high school. At Ikki's behest, he also takes up A.T.
Initially, he lacks the courage to stand up to the Skull Saders and verbally abuses Ikki and throws his A.T. into a nearby sewer. However, he and the rest of the East Side Gunz returned Ikki's A.T. to him, with the plea that he save them from the Skull Saders . Later, when Emily Adachi and Nakayama Yayoi are found to be working for the Yaou and were forced to set a trap for Ikki, Kazu stands up to Buccha and is hospitalized as a result. When Kazu is discharged, he becomes a founding member of Team Kogarasumaru, quitting the East Side Gunz despite being offered leadership of the team in exchange for Ikki's head. In their debut match, he shows his potential as a speed-type rider when he overwhelmingly defeats his opponent in a F-class "Dash" match against the Sabeltigers, earning him the nickname "Stealth". Later, he proves himself to be a match even for Yasuyoshi Sano of Behemoth, sparking an increase in his popularity despite his defeat.
After Ikki was hospitalized for a bone fracture, Kazu takes over Kogarasumaru as interim leader. Unfortunately, his first match as team leader, an E-class match against Animal House, was a disastrous failure. Subsequently, he goes through a deep bout of depression, further exacerbated by his helplessness in the fight against Gabishi. Kazu eventually recovers in the rematch against Animal House and he "awakens" to the Flame Road for the first time. He then successfully leads Kogarasumaru to B-class status.
When Ikki is betrayed by Sora, Kazu learns of the true history behind A.T. and Sleeping Forest via Spitfire, who chooses him as the successor to the Flame Regalia. He then witnesses Burnin' Blood (Aeon Clock and Spitfire collaborating) facing off against the Takeuchi brothers at Sano Tower and Spitfire's death. This causes him to antagonize Nike, and he undergoes training from Black Flame and a digital copy of Spitfire with renewed determination; however, he spirals into another fit of depression when the Flame Regalia is stolen. It is not until he joins a cult and gets mocked by Ikki that Kazu recovers; in the ensuing match, he shows off the fruits of his training and proves his strength as a rider despite the match ending in a tie. He was paired against Nottdagr, a member of Sleipnir. He eventually won by pairing up with Agito to create a flaming fang, a powerful combination attack that defeated Thor and Nott-Dagr.
When Kogarasumaru arrived on the battleship Colonel Sanders, Kazu descends the ship's levels alongside Aeon Clock, Agito, Buccha, and Onigiri in an attempt to rescue Rika Noyamano from her imprisonment. Unfortunately, he is quickly captured in a trap and becomes separated from his teammates. He is last seen suspended in a bubble on the ship's deck, near the area where Ikki battles Nue. As of 313, Kazu has appeared to confront Nike, along with Yasuyoshi Sano.
After rescuing Onigiri, Kazu and Aeon Clock proceeds to fight Nike, in an effort to avenge Spitfire's death. Despite the two Flame riders' combined efforts, Nike was still able to easily overcome them on his own. After Aeon's Phantom regalia is ripped from his body, he uses it to tune the Flame Regalia for Kazu and gives it to him just before his death. Kazu then proceeds to fight Nike as much as possible using the flame clones but Nike was able to easily attack all the clones. Kazu nearly escapes death by dodging Nike's fatal attack with his sword. Nike states he fight's dirty and isn't worthy of being his opponent and starts to walk away. As Nike's sword melts, Kazu said that he can now do it. He suddenly appears behind Nike with his hand on his back.
Following this attack Nike asks Kazu what he has did and Kazu replies that he did the only thing he could do. He is then joined by a figure of Spitfire seemingly formed from his own flames. He claims that the only thing he can do is borrow everyone else's strength, and he then produces clones of Nike's other victims; Onigiri, Yoshitsune, and Aeon Clock. Nike then lies injured from an unseen attack, claiming that Kazu has "opened that door". Kazu tells him to get up as he is not finished with him yet.
Kazu remembers how Spitfire urged him not to hate Nike, as Nike was merely being manipulated and used by Sora. Kazu however found it difficult to comply this request, and began to beat Nike, telling him to say things about how bonds and friendships are useless, so that Kazu can have no regret in killing him. At this stage Nike reveals a hidden, large missile that ignites and explodes with Kazu's flames. The two are sent to the lower level.
Kazu watches as Nike impales Simca with his claws in order to get rid of his impurity, and then turns her body temporarily rock hard with his gem road. He drops her, forcing Kazu to catch her because she would shatter and die otherwise. Kazu does this having no choice, but breaks his run and thus leaves himself open to attack.
Luckily, Benkei arrives and cuts off one of Nike's legs before Nike could do the same to Kazu. Kazu, having watched the damage Benkei took to herself from the attack, revitalizes himself and prepares to fight. He uses a large amount of energy and collides into Nike, nearly losing all his power. However he smiles in this excruciating pain, remembering that this is what Ikki would do, to prove to himself that he has not yet reached his limit. Ikki arrives and watches this, holding an alive Onigiri in his hands and congratulates Kazu on his efforts. He then encourages him to defeat Nike. Kazu uses all of his energy, even his life force, to use one final St. Elmo's Cross, burns Nike. Nike is angry at being underestimated, but Kazu claims he never does so, and simply gave it his best. He comments that Nike helped open Kazu's door, and watches as Nike is thoroughly burned and finally defeated by Kazu's attack. Kazu smiles, but is apparently caught up the explosion of his attack. However, Ikki finds that Kazu is still, if barely, alive. He gives Ikki his flame Regalia to make the Storm Regalia before passing out. He later goes to the hospital with Onigiri to heal his wounds and watches Ikki's fight with Sora.
3 months after Sora's defeat, Kazu is at a concert while Emily is singing in a band and she announces her love for him and finally asks him out and Kazu, while shocked, happily says yes. Since then the two became a couple.
Abilities and A·T
Kazu is classified as a Speed-type rider, emphasizing nimbleness and quickness in his style. His run is fast enough to appear invisible on film and to the naked eye, and he is capable of blitzing Om even when the back wheels of his A.T. are locked. Kazu eventually awakens to the Flame Road, and eventually becomes the presumptive Flame King. His repertoire mainly consists of "Time" Tricks along with the occasional "Flame" trick. Apart from possessing the King-Class abilities to merit the title of Flame King, Kazu displays considerable analytical ability, and is capable of dissecting and understanding the principles of opponents' moves instantly. He's also a copy master as he is shown being able to copy an opponent ability; Is ability Kazu learn during the battle against Aeon Clock.. Outside of A·T, Kazu is a competent fist-fighter and an incredible batter, although his batting form is horrendous.Kazu's A.T. are a mass-produced model whose exact details have not been revealed. Spitfire entrusted the Flame Regalia to him, only to have them stolen by Yasuyoshi Sano. As a rider, he is known as "Stealth", and his shadow is an F-18/A "Hornet", which later became a Pegasus and recently a knight riding a Pegasus. His shadow is currently a flaming four-winged unicorn. Kazu's initial R.E.A.D. level was 18, which drastically increased to 89 during the battle with Sleipnir.
After the death of Aeon Clock, the Flame Regalia was given to Kazu. It was shown that his speed has changed to a level wherein he could exchange blows with Nike, an opponent that he previously could not even touch. Nike estimated that his R.E.A.D. level was approximately between 200 and 250 at most; however, due to his speed and wide range of abilities he is capable of competing with riders who have R.E.A.D levels almost double of his, such as Nike. Due to the ability of the Flame Regalia to tap into SkyLink and access the "Runs" of other riders, he becomes capable of using Roads other than the Flame, such as the Thorn, Rumble, Smell and Wind with the Flame road as the base. However, doing so requires that the user be strong enough to handle the "Roads", otherwise he will be putting his life at risk.
- Super Stride IV "Sonic Boom" - Kazu moves so fast that he creates a sonic boom and he uses that to boom to attack his opponent, this seems to be a variation of Flame Road: After Burner is similar to the Sonia Road's Thorns.
- Flame Road: After Burner - Using the same principle behind a jet engine's afterburners, Kazu accelerates to supersonic speeds, creating a sonic boom and leaving tongues of flame where he made footfall.
- Time - Kazu accelerates his moves with his A·T to strike the joints that initiate movement on an opponent's body, effectively paralyzing them; however, it takes a great deal of stamina to perform. The speed of the attack and burning sensation that the user experiences categorizes it as a Flame Road trick.
- Shield of Time - By applying the principles of the Time technique to defense, Kazu is able to create a shield capable of slowing down attacks and reducing the impact of connecting blows.
- Flame Drafts - Kazu is able to create fiery flame drafts on his own. This was first seen during the battle with Sleipnir, which allowed Ikki to soar above them to get back to his plane.
- Clones of Flame - Kazu creates "clones", which are actually the afterimages produced by his run.
- Agito & Akito & Kazuma Grand Fang Fire Bird - Agito creates a giant fang while Kazuma sets it a blaze with flames making it easily capable of taking down a plane.
- Flame Lens - A move based from Sleipnir's Nottdagr "wind lens" trick to project illusions, which he used to project an image of the plane he and Agito were riding on.
- Cloak of Time - Makes the user and or who the user want be made invisible for a short period of time. This is achieved by using heat convections to reflect light via high speeds.
- Platform of Flames - Using the rising air current from the "Flames" his A.T.s create, Kazu can use them as platforms, allowing him to stay in the air. He used this trick in chapter 315 in an attempt to make sure he wasn't stopped by Nike's vibrations
- St. Elmo's Crossfire: While utilizing the Apollon Road with Aeon Clock's assistance, Kazu creates a cross-shaped blast of flame. Utilizing all his energy and life force, Kazu can perform this trick on his own.
- Trick: Hole Nine Heaven's Door [Ættir] - Kazu uses this in his fight with Nike. This trick enables the wielder of the Flame Regalia to perfectly replicate other riders' tricks and roads. This is made possible by the Regalia's connection with Skylink: it opens the "door" that seals the room containing the data file of every rider, and therefore the memory of their runs. However, the user needs experience and technique to able to use this technique perfectly, otherwise he will risk his life. Kazu utilizes this trick to emulate the Sonia Road's "whip" to break through Nike's Gem hardening trick; the Over Road's "windmill" to absorb Nike's aerial vibrations and transform them into heat energy; and the Smell Road's flame-amplifying abilities to strengthen his own flames enough to melt through Nike's armor. He later copies the Hurricane Road's wind barrier in order to protect himself from an explosive warhead.
- In her only appearance, Kazu's sister has her face covered by a speech bubble.
- Kazu constantly wears a beanie because he was a bed-wetter until the age of six, and he got used to the diapers his sister would fasten onto his head as a prank.
- On his first date, he vomited from nervousness and had to exit the theatre he was in.
- Kazu's shadow has changed a total of four times in the story so far, first it is a F-18/A "Hornet", then a Pegasus, and recently a knight riding a Pegasus. Though the F-18/A "Hornet" has been featured again after the two so the Pegasus or the knight riding it could be just a metaphor and not an actual shadow. Finally, it last changed in the current battle against Nike where his shadow was a four winged hybrid of unicorn and pegasus.
- In Chapter 250, Kazu is seemingly able to ride one of Agito's Fangs; this would make him a very basic Wing Road user.
- "Kazu", in Japanese, means "number".
- In the Manga he owns a dog named Chiwa.