During Cat's Eye's latest heist, an inauspicious circumstance has forced Ai to hide their objective - a huge diamond stolen from the Kobari Company - underneath one of the Inunari Precinct's police cars. However, the car in question is used by Toshio to take Hitomi for a joyride on the next day; the company's president, who is involved in many illegal businesses and urgently wants his diamond back, knows about the car's significance as well; and to top things off, a young, cocky thief promptly steals it for use as his personal racing car.