Kokoro Toshokan, a small library, lies nestled in an unpopulated mountain far away from town. Three sisters, Iina, Aruto and Kokoro, call the library home and run it from day to day. Kokoro is just beginning her adventures at the library. Will she become a full-fledged librarian? Will the remote library ever attract readers? Kokoro tries her best to make her dreams come true at Kokoro Library, a place where miracles can happen.