Read manga: Akarui Sekai Keikaku

manga
Summary:

The minister's aide has an idea, a project in mind to help correct the declining birth rates in Japan. This plan, so to speak, has it where Japan's youth are encouraged to form relationships. The catch is that at the chosen highschool for the initial test of this is being held, the project is mandatory — the students must become intimate couples with the other students or they will die.