His mother, Saki, is immersed in masturbation, letting out a seductive moan. Kazuya gasps at the lewd scene he accidentally stumbles upon. Surprise, confusion, excitement. Of the various emotions that well up within him, the one that shook Kokoro the most was Saki's lonely expression. "Mom, I'm lonely..." His father is not here tonight. He is the only one who can satisfy his mother. Seeing Saki in a frenzy, Kazuya decides to cross the forbidden line.