There is a series of three photos taken in the early 1900s of Kyoda Juhatsu (Tou’on-ryu founder) and Miyagi Chojun (Goju-ryu founder) demonstrating techniques. They are posing in front of a seaside backdrop and wearing what we today would call ‘board shorts’.
Looking at the photos, I do think it is swim wear that they were wearing. You see (no pun intended), modern ‘sea bathing’ (as it was called back then) began in Europe and the United States around the 18th century and was introduced to Japan during the Meiji era as a form of recreation and medical treatment. In addition, during Sino-Japanese War swimming became popular as way to strengthen citizens and the military. Okinawa, being an island, had no lack of beautiful beaches for people to take up this new western recreation.
It seems that specialized clothing for ‘sea bathing’ and swimming appeared around the late 19th century when the pastime became widespread. Most of the clothing was similar to the athletic wear of the time, which consisted of two-pieces, a loose-fitting top and shorts. This type seems to have been used continuously until the 1910s; around the time the photo of Kyoda and Miyagi was taken. In Japanese the shorts are referred to as ‘Kaipan’ (海パン), or ‘sea trunks’.
Examples of early 20th century swim wear
Still, I’m not sure why Kyoda and Miyagi chose to wear ‘kaipan’ for the photo. Perhaps it was simply because of the ‘swimming’ craze that gripped Japan at the time. Or maybe it had something to do the seaside back drop they posed in front of; it certainly looked nice. Perhaps they thought it was better than posing in ‘suteteko’ (long underpants ステテコ) or ‘fundoshi’ (loincloth 褌) which may have looked ‘low class’. I suppose we will never know. But I can say that they look pretty cool.