This paper addresses the research on the business history of the Anglo-Japanese rivalry. The NYK, a Japanese company and a newcomer to the Chinese waters in the early twentieth century, had challenged the ascendancy of the British shipping companies on the Yangtze. This paper also discusses the effects of the political support for both the Japanese and British companies. The Japanese shipping industry, backed by the Japanese Government, expanded their forces on the Yangtze by purchasing British property. The British shipping companies, with their own political support, initially overlooked the Japanese threats. However, later the British companies used British law to secure their own interests as the Japanese Government used diplomatic influence as a method of assisting Japanese business interests abroad. To conclude, this paper emphasises the critical role of political support in promoting the NYK expansion in this case study, which leads to a revision of the conclusions of some earlier research. This paper is also a survey on the Japanese imperialism, as well as a record of the decline of the British free trade policy in the early twentieth century.