Monster Musume summary: A revelation that shook the world occurred three years ago: the existence of legendary creatures like harpies, centaurs, and catgirls was confirmed. The "Cultural Exchange Between Species Act" was then established to integrate them into human society. Our protagonist, Kurusu Kimihito, a regular human, was assigned to take care of a beautiful lamia named Miia, as part of the government exchange program. His mission was to guide her in adapting to the ways of the human world. Nevertheless, the law prohibits interspecies breeding, causing Kurusu to struggle with his feelings towards Miia. The situation becomes even more complicated when a stunning centaur and a flirtatious harpy also join Kurusu's household. He finds himself in an utterly perplexing situation.