After school, Jinguji Ryugetsu is called by a girl and is confessed by her but he rejects her without hesitation. That's because he has a crush on his childhood friend. His childhood friend, Suzuki Nayo, has her birthday tomorrow. The two have mutual feelings but they're still just childhood friends. When Nayo invites him not only to celebrate but also to spend the night at her house, Ryugetsu is thrilled and decides to confess his feelings. Shortly after, Ryugetsu meets a certain man in a public restroom. The man speaks to him, they exchange a few words and then he leaves... When he looks in the mirror, he realizes that his face has changed ugly without him noticing. Ryugetsu becomes extremely anxious... and without knowing why, he attacks Nayo... Unable to resist Ryugetsu's exposed instincts, Nayo gradually...