Guilty

Guilty was the guardian of Death Queen Island. He, different of the majority of villains, don't fight with the heroes. He just is a bad guy.

Guilty, in anime, was brainwashed in the Sanctuary and because this, forgot all his fellings, and his daughter, Esmeralda. In the manga, Guilty is naturally bad, and Esmeralda is not your daughter, but, a slaver of an habitant of the island.

Guilty x Ikki
Guilty have teached Ikki to forget your good fellings, like him; according Guilty, the hatred is essential to win a fight. Ikki, initially refused this philosophy, but, when the Guilty attack hits, and kills Esmeralda, Ikki (that lived a Hell in the Island) becames a Demon Man, and kill Guilty. Before his death, Guilty says to Ikki where is the Phoenix Armor, and reveals Mitsumasa Kido is the Ikki's father.