Sanjiyan Henjō is based on the manga and anime series 3x3 Eyes. Pai, a young girl from the immortal tribe of sanzhiyan, three-eyed demons of Chinese origin, wants to become a human again. She meets a Japanese teenager named Yakumo Fujii, whom she accidentally turns into a "wu", an immortal obedient servant of a three-eyed demon. Together, Pai and Yakumo try to regain their lost humanity.