Yase is the daughter of Myoue and Koto. She was born out of a picture of a demon and thus, is a demon. At a young age she was depressed because she wasn't like anyone else, but her mother calmed her down and made her feel loved. Because of this, she has a strong lingering attachment to her mother. In present-day Kyoto, along with her brothers, she is one of the three council members of the City Through the Looking Glass and is a socialite who frequently hosts tea parties.