Namban screens are a well-known Japanese art form that was produced between the end of the 16th century and throughout the 17th century. More than 90 of these screens survive today. They possess substantial historical value because they display scenes of the first European activities in Japan. Among the subjects depicted on Namban screens, some of the most intriguing are ships: the European ships of the Age of Discovery. Namban screens were created by skillful Japanese traditional painters who had the utmost respect for detail, and yet the European ships they depicted are often anachronistic and strangely. On maps of the Age of Discovery, the author discovered representations of ships that are remarkably similar to the ships represented on the Namban screens. Considering the hypothesis that ships of some of the Namban screens are copies of ships represented on contemporary European cartography, the author realized that one particular historical event connecting Europe and Japan may be the source of these representations. This was the first visit of the Japanese Christian embassy, the Tensho Embassy, to Rome, in 1582. Its journey to Europe and its following visit to the Taiko, or first effective leader of Japan, Hideyoshi Toyotomi, may have been a trigger for the production of one of the most well-known Japanese artworks, the Namban screens.