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Hisui is Kohaku's motherly mentor in the manga series Wish by CLAMP.
Hisui is one of four Angel Masters of the four natural elements (fire, water, earth, and wind), her element being wind.
Hisui is the original reason Kohaku comes to Earth the first time, as the Angel Master disappeared during a meeting at the bridge between Heaven and Hell. She eventually reveals herself to Kohaku, and also reveals that she has made love with Kokuyo (Prince of Hell) and states that she and Kokuyo cannot return to Heaven or Hell because of it. In a one-shot at the end of Volume 3, it is revealed that Hisui and Kokuyo had frequent rendevous before or after the bridge meetings. When they finally made love, Kokuyo decided to take Hisui to Earth so that they could stay togeter. He removed his pupil and placed on her ear lobe as a sign of being beholden to her. It is occasionally seen when Kokuyo lifts Hisui's hair. Eventually, God declares Hisui stripped of her power as an angel master and banishes her from Heaven forever.
Shuichiro offers to let Hisui and Kokuyo stay in his house while they are hiding. When Shuichiro dies, Shinichiro tells them that they and Kohaku can stay there forever because Shuichiro would have wanted it that way. They stay for the next 100 years after pledging to look after the sleeping Kohaku and are a part of Shuichiro the second's life as well.