Yumi Narushima, a girl who loves bicycles, notices Naogawa Naou holding a strange object on the train. Upon realizing that the item Naou was carrying was a bicycle, Yumi finds herself speaking to him without thinking, leading to their friendship. As they grow closer through their shared interest in folding bicycles, the girls embark on a new adventure, riding their folding bikes and feeling excited about the wonderful encounters that await them.