The title "Yuu & Mii" is a pun on the English phrase "You and Me". Aimu Yuu (remark: his name sounds like "I'm you") is a boy who just moved into the equivalent of a boarding house.
Everything is not as it first seems, even the boy. Living in the same room is a ghost named Mii. The series is a combination of love, humour, and a general parody of anime and manga. There are a lot of weird characters in this manga.