Marina and Airi's single mother has recently gotten married. Their new step-dad seems like he'll make a loving father. Like a really, really loving father.
How to prevent your onii-chan from looking up other girls' skirts: 1. Be tsundere as fuck to assert dominance 2. Have sex with onii-chan 3. Repeat step 2 all day everyday 4. ??? 5. Profit
Seven years after running away from his cruel father and cutting all ties with his family, Kengo receives a desperate plea for help from his ten step-sisters. He decides to return home and help them escape from the clutches of his perverted father. But first, he needs to analyze the situation...with his dick.