Kyonyuu Kazoku Saimin

Story

Based on the erotic game by Lune. The protagonist - Yuuichi - fails the entrance exam and is currently attending prep school. Around this time, his father, who is almost never home, remarries and his family gains new members. The mature and alluring mother - Mifuyu, her gyaru eldest daughter - Natsuki, and subdued second daughter - Akiha. Yuuichi wants to welcome the new family, but living together with 3 women is too titillating. Together with the stress of examinations, it becomes impossible to suppress his libido. And then, a mysterious package arrives.

Synopsis via AniList (English).