In the late nineteenth century, as Japanese scholars, traders, and labourers began to cross the Pacific Ocean in ever greater numbers, Tokyo-based intellectuals started to think about the significance of the ocean for the upcoming century. One prominent articulation of this ‘Pacific age’ was the result of an intellectual dialogue between a young Japanese student, Inagaki Manjirō (1861–1908), and his Cambridge professor, John Robert Seeley (1834–95). Traditionally framed as a relationship of ‘influence’ from teacher to pupil, and thus from West to East, the emergence of the ‘Pacific age’ was in fact the result of a sophisticated modulation of ideas from Seeley's The expansion of England (1883) into the rapidly changing politics of early 1890s Japan. This article traces that modulation in Inagaki's published works between 1890, when he graduated from Cambridge, and 1895, when Japan defeated China in the First Sino-Japanese War. It argues that Seeley's analyses, in Inagaki's hands, gave a significant impetus to existing expansionist visions in Japan, and thus constitute one example of late nineteenth-century history being written in the discursive space between Europe and East Asia.