Kōzuji Kazumasa

 Kōzuji Kazumasa was a prisoner at Deadman Wonderland, and a former MMA fighter.

Background
Kōzuji was once known as the champion "The Pulverizer" of Mixed Martial Arts. He got sent to Deadman Wonderland for brutally assaulting a TV actress on a reality show who refused to exchange email addresses with him.

Personality
Kōzuji is a highly arrogant individual and often treats those whom he considers lower than him, poorly. He only thinks for himself and uses oppression to keep himself on top. He also demonstrates no concern for the lives of his own followers and will go to the extent of using his them as human shields despite their protests.

Prison Arc
Kazumasa was first seen harassing another prisoner in the cafeteria and taking his CP. Ganta accidentally bumps into him and Kazumasa points his attention to Ganta. He punches Ganta and says that he rules over everyone else. He forces Ganta to laugh at the other prisoner and leaves after that.

Kazumasa appeared again in the locker room before the Dog Race. Again, he starts harassing people, but Azami stands up to him. Kazumasa kicks and breaks Azami`s arm unabling her to participate in the race. Kazumasa tells everyone that he will win the race, or else. Ganta accepts, but suddenly Shiro appears and Kazumasa is about to punch her too. Ganta then throws a book at Kazumasa's face in order to protect Shiro and to stand up for himself. Kazumasa was about to attack Ganta when Makina stops them.

During the whole Dog Race, he tried hard to stay alive and win by cheating and tells his minions to kill Ganta, which they failed. During the final round it was him, Ganta, Shiro and other prisoners. He tries a direct attack on Ganta but fails after the panels collapse. While falling he kicks the ball from Ganta`s hands and throws a knife at him, which Shiro blocks with her body. He survived at the end with minor wounds and was approached by Makina who, knowing how he cheated, sentences him to serve a year in solitary detention. She also tells him that if he refused, she will stab him in the heart with his own knife, so he chooses the solitary detention.

Revolt Arc
After Deadman Wonderland was shutdown Kozuji, along with other death row prisoners, were transfered to other prisons and had their collars removed.

Differences between Manga and Anime

 * There are numerous differences to Kozuji of the manga and his counter part anime version:
 * In the anime, Yō Takami stated that Kōzuji was a successful Taekwondo and a Mixed martial arts fighter. His nickname at that time was "The Ultimate Warrior". When he met an actress on a variety show and she wouldn't give him her e-mail, he lost his temper and attacked her. He was sentenced into Deadman Wonderland after that.
 * Kazumasa first appeared before the Dog Race.
 * Azami's appearances were replaced by Yō Takami, leaving Kazumasa to break Yō's arm instead.
 * Kazumasa never told his minions to kill Ganta, due to them getting killed in the first episode.
 * Kazumasa was the only one left in the final round along with Ganta and Shiro.
 * Instead of attacking Ganta head on, he tries to intimidate Ganta, but gets hit by a ball in the face.
 * After getting hit by a ball, he tries attacking Ganta but fails after the panels collapse. He tries to get away but falls, getting impaled on the spikes bellow and dies.