Seitenshou Academy is famous in Shizoaki since there is a legend that angels were created there. Mitsuto is a student there who doesn’t like the monotony of everyday life: waking up at the same time, going to school and coming back home after classes. He cleans the old and unused three-story Building B by himself. One day as he was sweeping the floors, he ended up on the seemingly nonexistent 4th floor and finds a girl reading a book alone. Her name is Hinako, and soon after he can start seeing things and people that normal people cannot see. The secret of the angels is starting to become unraveled.

[From Hau! Omochikaeri~]