Normally, the sexual circumstances of the older and younger sisters are unknown to each other. However, the sisters who live under the same roof are in the midst of puberty. Even though they know that they have families, they cannot suppress their sexual desires. One day, a trivial incident forces the sisters to confront each other's sexuality. Although they are shy, they come out to each other about their sexuality. From there, their excitement gradually increases, and they feel intensely even though their older sister (younger sister) is right in front of them. As the pleasure increases, the distance between Kokoro and bodies becomes closer, and before they know it, the sisters are intimate with each other. The two feel each other at zero distance, and the texture of each other's skin and breathing further increases their excitement, reaching climax many times. Will there ever be an end to the two who come to each other over and over again?