I am not really into fundoshi (wearing them myself-- freeballer here), but I certainly enjoy seeing other men wear them. It's the traditional garment (actually undergarment) worn by most Edo era men under their kimono or yukata (before arrival of Perry's black ships circa 1857). For nearly a century, it was still used as underwear and the bathing suit for men, but it's popularity as an everyday article of clothing declined after the American Occupation introduced Western-style underwear for men.
It's now become garment of choice for many 'masturi' - Japanese traditional festivals - many of
which celebrate the coming of age of young men and involve some type of virility or fertility ritual or ceremonial tasks. A variation of it, the 'mawashi' is still worn today by sumo wrestlers.
In 'matsuri', groups of men (old and young) don the fundoshi (with or without happi coat) and parade the streets and shrine grounds carrying the heavy wooden floats (actually portable shrines, 'mikoshi'), heaving it up and forward with their loud chants and boisterous energy. Quite often when ONLY the fundoshi is worn - with nothing else - the festival is frequently referred to as a 'hadaka matsuri' or naked festival.
It's true that some department stores in Japan got the idea to 'rename' the fundoshi and market it as 'samurai pants' or something like that, but it's still rather a special item that most men wouldn't own. For example, how popular is the thong for underwear or a bathing suit? Still there are a few men who wear kimono on a daily basis (instead of Western suits or pants) so I'm sure that you can find fundoshi at department stores and speciality stores. Even if not don one publically, some men might like the masculine image of the fundoshi and may be wearing them undertheir western attire - sort of like men who like to wear a jockstrap instead of boxers or briefs.
A lot of men at the age of 20 (for both men and women) celebrate Coming of Age Day (2nd Monday in January) and some of them wear traditional kimono (and may be wearing a fundoshi underneath (although I have my doubts). Summer festivals and firework display bring out hordes of people, particularly young men and women, in the traditional lighter cotton print 'yukata' (cheaper version of the often outrageously expensive kimono). I bet a few men wear a fundoshi (or like I do - nothing) underneath.
Some of my Net pics on Japanese male bonding, including many with men in fundoshi:
Mr. Wada is photographer who specializes in Japanese festivals and seems to capture men in fundoshi at literally hundreds of festivals.
An online store's ad for fundoshi:
A blog by Japanese guy interested in naked and semi-naked men:
(He has several categories, included the one for matsuri and fundoshi above)
YouTube vid on how to put on (tie) a fundoshi: (in Japanese - for modesty's sake, the model is already wearing a fundoshi as the instructor demonstrates how to put on (over the existing one).
So you can imagine what it's like being where a lot of men are getting dressed in fundoshi. He explains in Japanese that most people can't get a fundoshi tied by themselves (you need a third or fourth arm). So you can see why I think male bonding is one of the functions of Japanese festivals - you have to get naked and up closer and personal with another guy and then groups of men in order to wear a fundoshi and participate.
Well, I was wrong about one thing - YOU can put on a fundoshi by yourself. The same instructor completes his training of the younger fundoshi wearer - and put him to the test. A follow-up section of the earlier video (see my last posting for the URL).
This time he starts out without anything on underneath.