20 years ago, Weve Aliens arrived at Earth to search for marriage partners. Weve are perverted and love interbreeding. With their advanced technology, they have solved all the Earth's problems to do with the environment, food, and resources.
Gen is a student at the prestigious Human-Weve school Shinryou Academy. Due to his late grandfather's words, he loathes Weve and believes that pure humans will eventually die out if something isn't done about Weves soon. However, Gen meets the Weve girl Mirika, who falls in love with him.