The production of Japanese enamels for porcelain decoration was thought to have originated from the direct and exclusive influence of Chinese potters who moved to Japan during the chaotic Ming to Qing dynastic change in 1644. Recent systematic studies have identified, for the first time, the crucial influence of Jesuit missionaries on pigment and enamel production in Japan from the late 16th-century. In particular, such first encounter laid the foundation for the continued influence exerted by European technology on Japanese art throughout the centuries. The present study has further identified European enamels used for the decoration of polychrome wares fired in Arita, the porcelain production center of Japan. This continued exchange not only marked the Edo period, but also extended into the twentieth century. For the first time, the lack of written records regarding the use of western pigments for enamel production caused by the persecutions of European and Japanese Christians has been overcome in the work herein presented. The nature of the imported materials has been firmly identified and characterized. The analytical results (EDXRF and Raman) have finally revealed how western technology and materials not only kept influencing Japanese art during the isolation (sakoku) period, but also accompanied the strong westernization process that marked Japanese history from the late nineteenth century. Moreover, the significant reverse influence of Japanese-made enamels on Chinese polychrome porcelain production in the late Qing and twentieth century has been fully identified for the first time. Furthermore, results show that the shift of the Pb mode of lead antimonate (Naples Yellow) is affected by the firing temperature for enamel decoration, and that this characteristic, along with the chemical composition, enables the identification of the origin and manufacture period of the yellow enamel.