Eris, an adorable cat girl alien from the planet Catia, visits Earth to conduct study and make friends with people. Kio Kakazu, a new high school student who hasn't had much interaction with ladies up to this point, meets the amiable extraterrestrial at a funeral service, and the latter subsequently moves right in. When he sees that Eri's ears and tail are real, he finds it difficult to believe his eyes. His neighbor's friend Manami and his instructor Mrs. Itokazu both believe it is impossible to have an alien standing in front of them.
However, something doesn't seem right about the two women. Who is the enigmatic Momiji and what are they up to? Eri's brief, lighthearted visit to Earth seems to cause a lot more stir than first thought.
