Jino, the reigning Hero's Cup champion, receives a letter inviting him to the Ultimate Watch Car Battle League, a competition infamous for its brutality. On the day of the event, his Watch Car Bluewill is taken by strangers on the way home, though he is eventually recovered. To put a stop to the scheme behind it, Jino conceals his identity and enters the league, with Bluewill going under the disguise of Bluethunder. The action movie is the second film in the Power Battle Watch Car franchise, about sentient miniature robot cars and the young trainers who battle alongside them.