Nestled atop a secluded mountain, the Kokoro Library struggles to entice visitors. Yet, for sisters Iina, Aruto, and Kokoro, it's a sacred duty to maintain the family legacy. Kokoro, envisioning a future as a librarian like her namesake, strives to match her sisters' dedication. With sparse foot traffic, the siblings pass the days with tea, conversation, and books. But when enigmatic guests start appearing, Kokoro delves into the library's enigmatic past, discovering a realm where tiny wonders unfurl.