This research note examines the complex transliteration practices used by the Jesuits in Japan during the late sixteenth and early seventeenth centuries, with a particular focus on documents related to the Imjin War, the Japanese invasions of Korea which occurred over the course of 1592-1598. The linguistic diversity of Japanese dialects and the multilingual environment of the Catholic mission in the archipelago resulted in significant variability in the graphical representation of native names in European sources. By analyzing these transliterations, I explore how the Jesuits' policy of cultural accommodation, central to their evangelization efforts in Japan, influenced both their understanding of the Japanese language and shaped the way they recorded native terms. To this end, this research note includes a comprehensive list of Jesuit transliterations of Japanese proper names and toponyms, along with their corresponding original forms, aiming to facilitate the coordinated use and comparative study of both missionary and Asian sources in historical research on the Imjin War.