Ai wa Sekai o Sukuu no ka!?

In a world where the number of women being born is decreasing and it's now mainly a male society. The scientists are trying to figure out a way to bring back humanity and fix this virus. One of the famous, upper class, bright, young and handsome scientist named Mikoshiba has come to the lower class area in order to help their research due to his interest in a cute, naive but average scientist named Niino who dreams of saving the world. Mikoshiba now moved in with Niino, has a theory in which he wishes to try out. His theory is that by them having sex and sexual relations that they might able to solve the world's problem!