Hisui is one of the four Angel Masters, each representing a natural element—fire, water, earth, and wind. Hisui's element is wind. He is the initial reason Kohaku first comes to Earth, as the Angel Master vanished during a meeting at the bridge between Heaven and Hell. Eventually, Hisui reveals himself to Kohaku and confesses that he has been intimate with Kokuyo, the Prince of Hell. Because of this relationship, both Hisui and Kokuyo are unable to return to either Heaven or Hell. Shuuichirou offers them a place to stay in his house.
For the next 100 years, Hisui and Kokuyo reside in Shuuichirou's house, pledging to watch over the sleeping Kohaku.









