Konna-San Kaku Kan Kei Tte Dodesu Ka Manatsu-Hen

During the summer at a certain school. There was female students called Saya and Rena. They loves each other and secretly have been in relationship for a while. The two had sex in the infirmary room where no one supposed to be there, but there was  a guy from art club, Tsukumo, who witnessed the obscene activity they did. Saya quickly approaches Tsukumo and asked him to keep it as a secret in exchange of pleasing him. But, Saya becomes addicted having sex with a male partner than doing it with her current partner, Rena.