While hanging out with his best friend Naoto at the Kitami house, Shinya realizes he left his cell phone on the way home. He rushes back to get it, but there's something suspicious about the house... Naoto is having sex with his mother, Yurie! Shinya can't take his eyes off her lewd appearance. Yurie must have noticed Shinya's gaze, as their eyes meet. He runs away in a panic, but the next day she seduces him in sexy underwear, saying, "I want you to keep quiet about my physical relationship with Naoto."