Older sister Reiko and younger sister Akari. They are famous for being close sisters who live nearby and both have their own families, but in reality they have extremely strong sexual desires and grew up competing with each other to see who can please a man the best. Then they find out that each other's sons have problems and they come up with an idea... Which one of them can solve it? In other words, it was a way to satisfy their sexual desires, to see who can satisfy their sons...