Tatsuya Miyama left the countryside to attend a university in the city.

After a long time, he comes back to the countryside during his summer vacation to see his parents. There he meets his childhood friends: Kumi and Haru Momozono.

Tatsuya's heart pounds seeing the sisters he had only known as children.

Afterward, while Tatsuya is sleeping in his room, he ends up having sex with Kumi who visited his room.

On the next day, while Tatsuya is going out with Haru, they go to a shrine to take shelter from the rain.

As he gets aroused seeing Haru's wet clothes, she figures out that he had sex with Kumi.
Unable to stop her advances, Tatsuya ends up having sex with Kumi.

Tatsuya's summer vacation filled with worries about the sisters and his future begins.
Source: DLsite