One day, Rikako returns home from shopping to find her son Nobuo reading a porn magazine. She snatches it away and scolds him, but once he leaves, she secretly starts using a pink vibrator on herself. However, Nobuo comes back earlier than expected and discovers the vibrator's cord sticking out from between his mother's legs. Panicking, she turns it on—and the sudden stimulation triggers an uncontrollable reaction from her half-aroused body. Caught off guard by this unexpected turn of events, the shocked and flustered mother and son find their forbidden bond deepening beyond the point of no return.