Yuri (63) and Kazuyo (58), two sisters who have both separated from their husbands and live alone, find their quiet lives disrupted when Kazuyo's son, Susumu, suddenly appears while she is talking on the phone with Yuri on the balcony. Susumu is in a state of half-incestuous arousal, and soon becomes intimately involved with Yuri and her lover, Koji. The three plunge into a world of pleasure, bringing shocking and intense changes to the sisters' everyday lives.