From SAKURA Chitose Fan Page:
Mika, a 16 year-old student gets really bad news: her cousin Arashi is coming to live with her and her mother! The last time she saw him was ten years before and it wasn't a very happy relationship between them, since Arashi spent most of his time making her life impossible.
Arashi has grown into a really cool-looking guy, but he is the same as always and the first thing he does when arriving is joke about Mika's breasts (or lack of thereof)!