Souichi used to fool around with women until he impregnated Sakurako. A woman from a very distinguished family. With no way out, he had no choice but to settle down and marry. One day Sakurako's little sister, Kikuno, approaches Souichi. Onii-sama, I have a very embarrassing problem.

I suffer from insensibility, I'm sexual frigid, can you help me?. She says. Souichi, having resigned himself to a life as a mere husband, feels delighted, "human resources" so close-by! Kikuno is Sakurako's little sister, she must have "potential". Souichi thinks.

Souichi immediately begins training Kikuno into becoming an anal slave.