Yuta spends his summer vacation at home alone with his cousin Kei studying. However, Kei's teasing of Yuta results in their mutual desire for each other flaring up unexpectedly. They instead spend the ...

The joys of summer break; warm weather, sun soaked beaches, time off from school, and in the case of Yuuta Yamauchi, a torrid love affair with your cousin. Summer Sis details the sexual relationship ...