Kazuki Muto
Buso Renkin - Kazuki Muto
Series Buso Renkin
Age 16 (17 at the end of the series)
Sex Male
Height Unknown
Weight Unknown
Alignment Unknown
I’m going to protect everyone but…who’s going to protect me?
~ Kazuki Muto

Kazuki Muto is the protagonist of the manga Buso Renkin created by Nobuhiro Watsuki.

Background Edit

Kazuki Muto was once an ordinary high school student. One night, he witnessed a girl being attacked by a giant, snake-like monster. To save the girl's life, Kazuki jumped in front of the snake's attack, getting pierced through the heart and killing him instantly. It turned out that the snake was a creature called a Homunculus, and the girl was really Tokiko Tsumura, an Alchemist Warrior who hunts and kills Homunculi. After fending off the Homunculus, Tokiko brought out a device called a Kakugane and inserted it into Kazuki's chest, the device acting as a replacement heart and bringing him back to life. The next day, one of Kazuki's teachers caught him alone and revealed himself as the Homunculus who killed him, and planned to kill Kazuki to keep his secret. While Kazuki tried to escape the Homunculus, Tokiko called him and revealed to him what Homunculi are, and what exactly happened the previous night. After being eaten alive by the Homunculus, Kazuki ended up awakening his Buso Renkin, using it to burst out of the creature's stomach and kill it. From that day on, Kazuki promised to help Tokiko rid the world of Homunculi so that no one else would get hurt by them.

Powers & Abilities Edit

  • Sunlight Slasher: Kazuki uses the energy from Sunlight Heart's cloth to propel himself forward for a quick and powerful piercing attack.
  • Sunlight Flasher: Emits a burst of bright light from Sunlight Heart's cloth to blind opponents.
  • Sunlight Crasher: Kazuki's strongest attack, which has him wrap his Buso Renkin's cloth around its blade and uses the energy from it to increase the speed and destructive force of his charge.
  • Energy Attack: An unnamed attack that releases the energy from Sunlight Heart's cloth in an area around Kazuki, incinerating enemies in a circle around him. However, he has only used this attack once.

Equipment Edit

  • Black Kakugane III: A Kakugane is a device used by Alchemists to summon their Buso Renkin. After being stabbed through the heart and killed by a Homunculus, Kazuki was brought back from death by having a Kakugane inserted in his chest, replacing his heart. Because of this, being stabbed through the chest is no longer fatal for Kazuki, as he has no heart to pierce, though he can still feel the pain. The Kakugane also grants Kazuki a regenerative healing factor, which allows him to heal quicker.
  • Sunlight Heart: Kazuki's Buso Renkin, a weapon made from the Kakugane resonating with the wielder's fighting spirit. Sunlight Heart takes the form of a lance with a decorative cloth attached to it. This cloth can transform into energy with Kazuki's own willpower, which can be used to propel himself forward, or soften the impact of a high fall. If Kazuki somehow gets his hands on another Kakugane, he can transform it into a second Sunlight Heart, allowing him to dual-wield them.
  • Sunlight Heart Plus: Kazuki's evolved Buso Renkin, which was formed when Kazuki's and Victor's Kakugane resonated with each other. Though it's smaller than the original Sunlight Heart, and lacks the cloth, it can still release energy like the cloth could to propel Kazuki forward. It can also fire blasts of energy, and discharge the energy generated by Kazuki's willpower.

Alternate FormsEdit

  • Victorization: Due to possessing a Black Kakugane, Kazuki can transform into a powerful being called a Victor when utilizing his intense fighting spirit. In this state, Kazuki's strength and speed increase, he gains a healing factor that can regenerate lost limbs, he can drain life force from others to restore himself, and he can survive without oxygen. However, he is unable to turn off his life force draining abilities in this form, as it is a vital bodily function for Victors.

Feats Edit


  • Can lift and swing his massive lance without much difficulty.
  • His lance swings can create shockwaves.
  • Blocked blows capable of slicing through walls.
  • Has defeated Homunculi that are much larger than him.
  • With a single strike, took down a giant Homunculus.
  • Pierced Victor's hand.
  • While Victorized, could match Victor in strength.


  • Intercepted strikes from Tokiko's Valkyrie Skirt.
  • Dodged blows from a humanoid Homunculus.
  • Caught Victor off-guard while Victorized.


  • Survived being repeatedly stabbed through the chest.
  • Got back up after being smashed through a wall.
  • Survived being slashed fourteen times and got back up.
  • Survived punches from Captain Bravo.
  • The Kakugane in his chest is tough enough to block slashes capable of slicing through flesh and bone.
  • Survived being smashed into a building's roof hard enough to make a crater while Victorized.


  • Trained by Captain Bravo in combat.
  • Has killed and helped kill many Homunculi.
  • Defeated Papillon, a humanoid Homunculus, in their first battle.
  • Defeated Shusui Hayasaka, a Kendo master, without using any of Sunlight Heart's techniques.

Weaknesses Edit

  • Since his Kakugane acts as his heart, his Buso Renkin being destroyed or separated from him for long periods of time will kill him.
  • Sunlight Heart is heavy, and not useful for stealth or surprise attacks.
  • In battle, can't use the Kakugane's full healing potential, since using one as a Buso Renkin draws its focus away from healing. However, using an extra Kakugane to heal can remedy this problem.

Fun Facts Edit

  • Kazuki's name is a reference to the Yu-Gi-Oh franchise, with him sharing his first name with the creator of Yu-Gi-Oh, Kazuki Takahashi, and sharing his last name with the main character of the series, Yugi Muto.

References Edit

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.