Masaaki, who was raised with lots of love from his mother Iroha, is a total mama's boy and has no sexual desire for Iroha. The two are already in a sexual relationship and secretly have sex on a daily basis. Even though her body desires Masaaki, Iroha is aware that she herself is not capable of arousing him, which creates a dilemma. On this day, the two husbands suddenly decide to go on a trip together, which makes Iroha feel a little uneasy.