妹の友達の美人ヤンキーＪＫ　世間知らず過ぎて世話を焼いていたら惚れられました (Associated Names)

Onii-san is the man who can make me grow up! Marry me! The room of a university student with zero love experience, Tsukasa, has become the hangout spot for his younger sister, who made her debut as a yankee when she entered high school, and her friends. One day, he found a bulge on his…