Azusa Saitou

She was kidnapped and held captive when she was young. She eventually managed to escape, but was raped by the man with red eyes who is now Yakumo’s biological father. She tried to kill Yakumo when he was young because of his red eye as she thought because of that red eye Yakumo will kill people. Eventually Yakumo realized his mother truly loved him for his existence regardless of his red eye.

In volume 5 of the light novel, she appeared as a spirit to protect to protect Haruka and Yakumo when Yakumo’s real dad was about to hurt them both - Yakumo had been kidnapped and kept at the place where Azusa was kidnapped and raped at in the past - because of this they got away safely without any further injuries. Azusa’s remains was discovered to be hidden in the wall of that place. She was killed after she disappeared after trying to kill Yakumo.