[WiP]

About
Buruma (Japanese: ブルマ) is the Japanese term for Bloomers, which were used as PE outfits in Japan in the 20th century. Not to be confused with gym outfits in general, buruma refers to the specific underwear-like gym shorts part of the outfit. Despite no longer being used officially in present day, their close resemblance to underwear made them a common form of fanservice in anime and manga and kept them alive as a fetish item amongst its fanbase.
Origin
According to books on the history of Japanese sports,[1] buruma were introduced in Japan as women’s clothing for physical education in 1903. Initially introduced for ease of movement, the PE outfit changed its appearance several times throughout the 20th century.[2] The final change in appearance occured in the mid-1960s; resulting in the pittari (tight-fitting) buruma, which were a drastic minimazation from previous versions (shown below). This lead to the pittari buruma having the drawback of not always covering underwear. However, concerns over this were borne largely in silence until the early 1990s, when schools and individuals began to choose sports shorts instead due to the exponentially increasing modesty concerns; resulting in a rapid decrease in buruma use in the following decade. Nowadays, the usage of buruma as a required PE uniform in Japan has mostly disappeared.

Later Style (left) | Early Style (right)
Spread
The buruma’s revealing nature and close resemblance to underwear lead to the bloomer becoming a popular type of clothing fetish. Despite it no longer being used officially, the piece has survived through anime and manga where it’s frequently used as a form of fanservice. Although the fetish commonly extends itself to the PE outfit, the buruma has remained the most consistent throughout these fanworks; buruma fanworks often feature additional elements, most notably having the character wear a track jacket over the shirt or thigh-highs instead of socks (shown below).


Examples utilizing the Track Jacket and Thigh-Highs
[WiP: Mostly the Pixiv and Booru stats]