The story centers on a 13 year old boy who is pushed around by a mysterious 17 year old girl. First she forces him to let her move in with him, then she takes his bed and that's only the beginning. What's in store for this innocent 13 year old boy whose life is being throw upside down by this girl!?

Ah, the dream of 13! Kouta is our normal everyday boy, living with his fun-loving workaholic father. Lusting after the school idol in his class, playing games with his friend… there's nothing especially noticeable about him. But one day his father has to transfer to Sapporo and then appears a girl who volunteers to be Kouta's live in caretaker. And what a girl!

Everything about her is mysterious: her mysterious incredibly showy body, her mysterious interest in our boy, and her mysterious need to sleep in the same room… Doki, doki…