One day, Jun visits the home of his co-worker Hattori, and is completely captivated by his mother Keiko's elegance and her sensuality, which is hard to believe for someone in her 50s. Then, whether or not she knows Jun's intentions, Keiko starts flashing her panties from under her skirt... Jun is left flustered by the provocative sight he accidentally sees. Eventually, Keiko's maternal instinct is ignited, and she approaches Jun with even more extreme seduction, eventually chasing her son away and leaving him alone with her...