Okumura had always been obsessed with Yuna, his friend Kota's mother. One day, after staying over at Kota's house, he drugs Yuna, strips her naked, and secretly photographs her with his mobile phone camera. Later, he sneaks into her room and is caught rummaging through her underwear. He then threatens her by showing the lewd photos he took. Yielding to his blackmail, Okumura begins ravishing the body of his best friend's mother—the woman he's always desired. From that moment on, Yuna is deprived of her bras, forced into a daily humiliation of having her large, bare breasts exposed and mercilessly teased.