The protagonist, Aikawa Kouya, is infatuated with his childhood friend Yuzuki Yui, who lives in a nearby mansion. Although they barely made it into the same school, Kouya is struggling academically. Perhaps fueled by this anxiety, he feels powerless to stop his own personality from darkening. His younger sister, Miyuki, seems to dislike him, making him even more depressed. One day, Yui's friend, Kakei Kyouko, tells him that Yui desires to be sexually assaulted. Although the protagonist thinks it's impossible, they find themselves alone together, and he unknowingly sexually assaults Yui. Although he felt her earnest resistance was acting, seeing her crying her eyes out, Kouya realized Kyoko's words were false, but it was too late. Although afraid of being reprimanded by Yui for being forced, he first asked Kyoko for her true intentions. However, even after hearing the reason, out of anger at being deceived, he also forced himself on Kyoko. Afterwards, Yui was completely focused on the protagonist, while Kyoko, perhaps out of guilt, did nothing. The protagonist, beginning to sense a similar aura emanating from both of them, began to wonder if they truly desired to be forced, and whether he could discern the truth. While conflicted, the protagonist, beginning to experience pleasure from forceful actions, resolved to completely corrupt Yui.