In a secluded village called Kinase, known as "a village protected by god," siblings Kaya and Rin have grown up surrounded by a deep forest. Though they are not related by blood, they live together peacefully and share a close bond. Beneath their quiet daily life, however, a hidden secret lingers—one that neither of them has yet revealed. The title story, Nemurenu Chou (Sleepless Butterfly), follows the quiet unease that surrounds their relationship and the mystery of the village itself. The volume also collects three additional short stories. In Kaze ni Hana ni Kimi ni, a girl named Erika meets Ryousuke, a boy from Tokyo who once had a fierce passion for swimming until a shoulder injury forced him to give it up. Having loved the sea deeply, he has lost all hope and direction. Erika reaches out to help him find a new reason to live. Monochrome World centers on Jun, who has seen the world in black and white ever since a childhood Christmas Day. Carrying the burden of that secret and the memory of a past betrayal by a friend, she has kept her condition hidden for ten years. An unexpected reunion begins to change things. The final story, Alice, rounds out the collection with its own bittersweet tale. Each narrative explores themes of hidden truths, emotional wounds, and the quiet search for connection against the backdrop of everyday life.