My step-sister, who I got from my father's remarriage, has completely lost all her sexual sense!? The hugely popular immoral doujin work by the circle Shin Seido☆Honpo has been made into a long-awaited adult anime! My father remarried, and I got a new step-sister who's the same age as me. What's more, the boys in my class use my step-sister as their masturbation toy -- she's the smallest classmate in school, with the biggest breasts! But for some reason, she thinks that it's up to the older sister to satisfy her younger brother's sexual needs, and she keeps trying to satisfy my sexual desires...