Kiryuu Reika

A bewitching and ageless widow. The mother of the protagonist. She is the current acting head of the family and no one can stand against her.

The protagonist has few memories of his mother, and although she is his mother, he feels somewhat bitter toward her.

She appoints the protagonist as the next head of the family and instructs him to stay in the area.

Spoiler

Reika is actually Hayato's grandmother. As a demon living on Earth she cannot survive long outside hell. In order to continue living on Earth she feeds on the energy of other demons but since there are none she came up with a plan to have her children inbreed for many generations to keep their demon blood strong for her to survive on.