Based on the erotic game by LiLiM DARKNESS.

Childhood friends Rio and Mamoru. Although they know each other's feelings, their unclear and ambiguous relationship leads them to despair....... Rio becomes involved in idol activities after accidentally participating in a beauty contest. Mamoru is warned that Rio is a prize for "Sacrifice", a way of passing the time for the black-hearted and powerful. To protect Rio, Mamoru decides to get involved as a part-timer and participant, but he is unable to tell Rio about the true situation. He was trying his best to protect her, despite her confusion and suspicions. However...... The reality that confronts him...... Mamoru is shown a scene he does not want to believe or see. With a desperate cry, a naked Rio reaches out her hand for help. Mamoru was unable to grasp her hand......

(Source: Getchu, translated)