Onii-chan Ecchi Shiyo?

Anzu Yamashiro has loved her big brother for as long as she can remember and stubbornly refuses to do anything without him, whether it's going to bed or taking a bath. One day, she enters her brother's room and finds a dirty magazine, which leads to her discovering masturbation. At the same time, her brother arrives home. When he opens the door to his room, he is both shocked and aroused by the sight of his little sister masturbating on his bed. He becomes so aroused that he rushes to the bathroom in order to masturbate himself. From then on, the little sister tries to seduce her big brother in various ways: kissing him when he's asleep, taking off her clothes in front of him, and even stroking his penis. Can the brother resist the advances of a child?

[Edited from DLsite English]