While playing happily with his best friend Naoto in front of the Kitami residence, Shinya realized on his way home that he had forgotten his mobile phone. Rushing back, he sensed an unusual atmosphere inside the house. He discovered Naoto intimately touching his mother, Yurie, and Shinya became unable to look away from the lewd scene. At that moment, Yurie noticed Shinya's gaze and their eyes met. As he panicked and tried to flee, the next day Yurie approached him, begging him to keep quiet about her relationship with Naoto—and seduced him while wearing erotic lingerie.