Based on the eroge visual novel Harukoi Otome ~En de Gokigenyou~ by BaseSon.

Harukoi Otome revolves around protagonist Akihito Hayasaka, a male high-school sophomore. The high school he attends St. Francesca Academy used to be an all-girls school, and still has a high percentage of female students. Akihito's younger sister (Umi Hayasaka...