Art critic and collector Philippe Burty (1830–1890) was one of the first friends the Japanese interpreter (and future art dealer) Hayashi Tadamasa (1853–1906) made on arrival in Paris in 1878. The previously unknown letters translated into English within this essay present Hayashi’s work in Paris (1878) and Brussels (1880), his first impressions of Normandy (1882) and New York (1886), and his explanation of the evolution of Japanese painting (1885). They furnish valuable insights into the cross-cultural aesthetics that led the Japanese, the French, the British, the German, and Americans to collaborate in the development of the phenomenon now known as Japonisme, thereby filling in some of the information gaps surrounding Burty’s international networks and Hayashi’s early years in Europe.