I won't forget. I won't let it become just a memory. No matter who you are. The Terada family, by their father's orders, are to live in an abandoned inn for a certain period after graduating from high school. The third son, Taninosuke, is also to go there, but before he leaves, his father gives him two instructions. One is to keep a diary. And the other is... A strange tale of supernatural beings from long ago.