Yakumo Fujii was just like any other 16-year-old Japanese high school student until he ran into a strange girl named Yakumo one day on the way to work. She called herself Pai and claimed to be the last of the three-eyed race called the Sanjiyan Unkara, a race with the power of eternal youth. The series of events that follow their meeting binds Yakumo's existence to Pai's. Many demonic creatures are seeking Pai and her power to grant immortality, and a long, hard road lies ahead for Pai and Yakumo. However, Pai has a great deal of strength beneath her youthful exterior. Yakumo soon realizes his feelings for her are deeper than he imagined. He will always fight to protect the girl he loves.