Kazuki spent ten years eagerly anticipating the return of her neighbors to their former home, hoping for a chance to express her affection for her childhood crush, Yuuji. During their younger years, Kazuki and her sister Hatsune would play with Marie, Yuuji's sister, but as they reunite, Kazuki's reverie about Yuuji is dashed when he displays unacceptable behavior. Left to coexist and rekindle their youth in the absence of both families' parents, their situation grows ever more turbulent as they all enroll in the same school.