On a rainy night, Yuto, a freelance illustrator, encounters a mysterious girl named Milk with cat ears in a back alley. After taking in the non-human girl, Yuto’s once-quiet daily life becomes lively and warm. Milk's pure and innocent reactions to modern civilization gently heal Yuto's heart. As they spend time together, the two gradually form a bond as if they were a true family. This is a heartwarming visual novel about the gentle connections that transcend species and background.