Mitsuru Takahashi is a 19 years old technical college student, who has a preference for early teens, especially middle schoolers. He grew up in a motherless family with only his father. One day his father invited him to eat together at a restaurant. Noticing a woman could be involved from his father’s recent behavior, he realized that his father wanted to talk to him about remarrying. The woman that his father introduced, who would become his step-mother, was a 25 years old former hostess… Moreover, the step-mother’s two sisters, a second-year middle schooler and a sixth-year elementary schooler, would also live together with him. Mitsuru expected to live a storylike life where he could flirt with his 6 years older sister-like step-mother and his 2 little sister-like aunts. A new family, with beings similar to sisters. Thinking of his new life, Mitsuru’s crotch was beginning to swell in expectation! It’s the well-known sister-in-law story. This is a story about starting a friendly yet a bit dirty life with little sister-like beings and an older sister-like mother.