A young man is determined to have as many affairs as possible but not to get married. One of his conquests is of a different mind however. For she is pregnant and so he agrees to live with her. But he misses very much the other younger girl whom he saw a lot of, and with the older woman's consent, sees the younger one and on her request, asks her to move in with them. This is the beginning of a very strange triangle which they all live through to a not unhappy ending.

「性の美学」なる論文で評論新人賞を得た佐分利には、性格の全く異なるふたりの女性がいた。やがて、3人の奇妙な共同生活が始まるのだが…。