Yoriko Nagata

A young man in his last year of middle school trying to get into the same highschool as them is constantly being seduced by his slightly older step-sisters. The series revolves around his struggle to balance his school, and personal life with his sisters affections. Takes place in modern Japan. (imdb)

After his single father gets remarried, Keita Suminoe not only finds himself with a new mother, but also two beautiful twin step-sisters, Ako and Riko. Their close bond as children soon grows into something more personal, and Keita finds himself in a real bind that he vigorously struggles to escape from. (myanimelist)