Aoyagi Seimei (青柳清明)
Seventeen years old, and this story's most wanted man, so to speak. He faked his own death, for unspecified reasons, and left behind a lot of angry people. Some wanted to kill him themselves (Septimal Moon), some just disliked him (Nagisa, Ritsu, Yamato), some were left in the lurch (Soubi), and just one didn't care why he did it, he just wanted him back (Ritsuka).
Depending on who you listen to, Seimei is either a bastard or a prince. Like Soubi, he treats some people like gold, some like slaves, and the rest like trash. There are only two people in the world to him: Ritsuka and himself. As Seimei himself says, "The rest of humanity doesn't concern me."