A young and ingenious girl by the name of Jun spends most of her time creating a variety of things, including two miniature robots named Kichinosuke and Yukinojo, which quickly become her closest confidants. Though intelligent, Jun enters college at a young age and is mocked by peers for being small and youthful. Another student in her class, Zero, is ostracized for previously falling behind in school and being more interested in motorbikes than academics. However, their mutual passion for mechanics brings them together, and Zero agrees to dine with Jun at her family's restaurant, Harbor. As they embark on new adventures and engage in heated discussions, Jun finds herself falling for Zero, despite his being twice her age.