Ryo Sakazaki and Bob Garcia are a mismatched pair of friends; Bob is the heir to a fortune and dresses in white suits; Ryo wears ratty workout clothes and runs a karate dojo. Their friendship is based on a shared love for the martial arts, their devil-may-care attitudes, and Bob's affection for Ryo's sister, Yuri. While pursuing a lost cat, Ryo and Bob stumble onto a mob hit and get caught up in a high-stakes game of cops and robbers. Both the cops and the robbers think the rakish pair has found the stolen diamond, the fabulous Eye of Sirius. Mob boss Mr. Big kidnaps Yuri and manic police lieutenant Todo tries to arrest the pair. Bob and Ryo have to find the gem to save Yuri - and themselves.