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.