Yabuki Nako is an upcoming college student from the U.S who transfered to Japan on her first semester to live with her grandmother in their century old Minka style residence.

One day, when she was bored, she tried to roam around the place to familiarize herself with the new home. After a few turns, she stumbled upon an abandoned room at the east side of their residence, and as if like a child, her curiousity led her into entering the room, only to find a small wooden box placed at a shelf, with an engraved letters, E + S.