Reiko, a married woman from the same apartment building, constantly tempts him with the dark, indecently colored nipples peeking from her neckline. Starved of female contact while studying for another entrance-exam attempt, he finds the sight impossible to resist. When she brings him breakfast and carelessly exposes her cleavage again, he loses control and plays relentlessly with her nipples. She stiffens, writhes, and cums before his eyes, beginning a daily routine of obsessive nipple teasing.