One night, when Kiyoshi and Koichi stayed over at Hiroyuki's house, Kiyoshi went to the bathroom and heard eerie moaning sounds from inside. It was Hiroyuki's mother, Kanako, masturbating. Unable to resist, Kiyoshi approached Kanako and initiated a sexual encounter. Koichi, who had been secretly watching, soon joined in, and Kanako was taken repeatedly by the young men, escalating into an intense orgy.