The "Bobby" mentioned in the title is actually 17-year-old Akihiko Nomura, a struggling high school student with a profound passion for motorcycles. His grades are poor, and his father—traditional and strict, though he must have eventually relented and allowed him to own a motorcycle—is doing everything he can to persuade the boy to apply for college. His mother is so quiet that she might as well not exist. In reality, his support system consists entirely of his lively little sister, who is nosy but cheers him on in her own way. Bobby does little else but work on his bike. He cleans it, tunes it up, and rides it. One might call him a motorcycle otaku. His most recent achievement appears to be having photos of himself on a road trip published in a motorcycle hobby magazine. This leads to an unexpected outcome: a girl his age, who picked up that issue on a whim, decides to write him a letter. It is a long, rambling letter, yet dreamily romantic nonetheless. Bobby admits to his sister that he has never received a letter from a girl before. He writes back, "I got your letter. I'm happy 'cause it was from a girl." Bobby is not a well-rounded kid. He barely speaks—even to his own family—and the "letters" he writes back to the mystery girl usually consist of a single sentence or so. His obsession is all-consuming, to the point where he happily quits school to work at a biker bar. Naturally, his father, at a loss, kicks him out of the house. While staying with a friend, he is delighted when his female pen pal says she will call him. On that day, his boss at the bar decides to take him to a motocross track. But that is a day that would not end in a way that anybody would expect.