Aizawa Kiyoshi has recently lost his childhood friend Kazuki Hikaru to a traffic accident. Not still quite feeling the reality of the situation, a certain day he awakes to see Hikaru in his room.
Only she didn't have the size of a normal person, but was only about 25 cm tall.
"Well, I can't return to school like this, so I'll be in your care for a while!"
So their strange cohabitation starts...