0ne

0ne is the finished version of Zer0, he enjoys life but doesn't understand why everything should live. He is intrigued by Zer0's way of looking at life, he stands by Zer0 and makes sure he doesn't go to far. He thinks of Tatsuya as a person who hasn't fully seen what humans and thinks Tatsuya should be the one to kill him and Zer0. one believes that both humans and Oxidans should disappear.

NOTES: one was originally going to betray Zer0 and Doctor Kyu in the first episode and become a Kamen rider called "Kamen rider Radiant", who would be more killer and fierce then Zer0 when transformed.