While their parents are away on a business trip, the one entrusted with watching over his younger sisters is the big brother, Souichirou Nanase. Summer vacation has just started, and the siblings are bound to spend a lot of time together. However, Souichirou soon realizes that taking care of five adolescent girls—Michika, Koharu, Hiyori, Rio, and Aya—may be more troublesome than he expected. On top of having distinctive and quirky personalities, the girls are at that age when young women tend to experiment with their bodies and ask "those" questions. To make matters worse, Souichirou has a sister complex, and the five temptations walking around might be enough to finally break his moral barriers. [Written by MAL Rewrite]

Humanity is undergoing a dire crisis: women densely populate a world in which almost no human male can be found, the ratio being one man for every 10,721 women. To solve this grim predicament, governments issue licenses to men, encouraging each to copulate with girls of their choice in hopes of restoring the balance between sexes. As the only male in his city, Takumi Ibuki receives his license and goes about his duty. In an environment where there are females as far as the eye can see, whether it be with his school's ace, with his childhood friend, or even with his sister, Takumi will do his best to save humanity from its impending extinction! [Written by MAL Rewrite]

A former science teacher receives a mysterious recruitment document, inviting him to a prestigious school. However, this school is not what it seems...

Two high school friends get a part-time job on a luxury summer cruise vacation, where they'll have to cater to all the VIPs' wishes.