Tsunenaga Tamaki

A major antagonist form the first half of the story, Tamaki is Assistant Warden and de facto tyrant of Deadman Wonderland. Under his calm, almost idiotic attitude, he is something of a sadist, caring nothing about the fact that he butchers dozens of prisoners every day for the sole purpose of gathering money or experimenting on them, or simply for his amusement. As son of the dying Chief Warden of Deadman Wonderland, he eagerly hopes for the death of his father to become truly the supreme ruler of the prison, and he devotes much of his time and resources in studying and experimenting on the powers of the Branch of Sin and their origin.

He also is in contact with the upper echelons of the Japanese government, his ultimate goal being the synthesis of artificial Deadmen. In sharp contrast with his cruelty, he enjoys playing with children toys.

(Source: Wikipedia)