Jun is a precocious young girl who spends her time designing and building various inventions. Her latest creations are two robots, Kichinosuke and Yukinojo, who become her constant companions. Jun enters college at a young age, where she meets Zero, a classmate with a passion for motorbikes. Zero's unconventional approach to academics has led to him being older than his classmates, and he faces ridicule as a result. Jun, on the other hand, is much younger than her peers, and she faces similar teasing. Despite their differences, the two form a connection over their shared interest in mechanics, and Zero agrees to meet Jun at Harbor, a restaurant where her parents work.