Inma-tachi no Yuugi: Ittara Owari no Isshuukan

Behind the graceful and perfect honor student Mari is a demonic sex fiend that feeds on semen by night. But this time, she's been stopped in the act by some powerful incubi, and her power to invade dreams is stolen away from her.
The condition for her full release? A week without climaxing under full pleasurable titillation in the dream world...