In the early 1990s, a tractor mechanic from China nicknamed Steelhead (Jackie Chan) enters Japan illegally, in search of his girlfriend Xiu Xiu (Xu Jinglei). Steelhead and his friend, Jie (Daniel Wu) meet in the busy Shinjuku district of Tokyo and take manual labouring jobs to earn money. When Steelhead finds out that Xiu Xiu has married a Japanese Yakuza leader named Eguchi (Kato Masaya), he decides to remain in Japan. When Eguchi was targeted to be murdered, Steelhead saves his life. To consolidate power, Eguchi formes an alliance with Steelhead to carry out his revenge. Soon, Steelhead has become embroiled so deeply in the ways of the yakuza that there is no turning back.