Since a long time ago, Tenjo Yuuya has always been bullied.
He goes to high school while living alone at his late grandfather’s house.
Although he was always met with severe bullying, he found solace during the school breaks.
During this time, while cleaning his grandfather’s house, he also decided to clean the room where his grandfather keeps the items he collected throughout his life. A room where Yuuya has never entered before.
While trying to organize the items collected by his grandfather, he found a mysterious door that was seemingly cut out from the wall.
Out of curiosity, he opened it. And then———-.