PAIS-035 Invite your friend to fuck your stepsister

The number of experienced people is 1, exactly 1 time. When she loses her virginity, she spews out, soils her boyfriend's room, and is dragged away. Since then, I haven't done H, and I feel complicated. Not only that, but she doesn't like having big breasts, so she's a meek girl who bows her head. I applied because I wanted to change myself, but...