Kazuo Kiriyama (桐山 和雄, Kiriyama Kazuo?) is a fictional character in the best-selling Battle Royale novel and manga by Koushun Takami. He can be viewed as the main antagonist in both versions. He is also a character in the film of the same name, played by Masanobu Ando.

The characters in his first name mean "peace" and "male," respectively. The characters in his familiar name mean "tree" and "mountain."

In the novel and manga, it's implied that he was a product of maternal infidelity. After killing his gang in the novel, he touches his left temple due to some elusive feeling he infrequently has. Kazuo states that since the doctor who operated on him died and, as he puts it, "his real father" dying of complication, he has no one to question about this.

Source: Wikipedia