When you read about the fundoshi making a comeback in Japanese department stores, what's being referred to is usually etchū fundoshi.
Etchū fundoshi are a simplified variation of fundoshi. Still a rectangle of cloth, the main differences are that the rectangle is about half the length of a rokushaku fundoshi, and there are two ribbons or strings sewn to the corners of the rectangle. These ribbons are tied around the waist, forming the "belt" of etchū fundoshi.
The cloth rectangle falls from the small of your back, then is drawn up between your legs and pulled under the strings, forming an apron that hangs in front of you. Etchū fundoshi are remarkably light and cool, feeling barely there at all against the skin, and are virtually invisible under clothing. For a person who is interested in fundoshi, but whose tastes tend towards boxer shorts for their freedom and comfort, Etchū fundoshi rule all over boxers. They are lighter, sexier, and don't ever creep up -- the plague of boxers.
Etchū fundoshi also offer the greatest variety in appearance. Not only can the apron be long or short, but they come in a dizzying range of colors, stripes, tartans, patterns, and prints. Often, the apron portion is decorated with silk-screened designs, i.e. dragons, anime characters, flower blossoms, or kanji.
Although perhaps not quite as easy to make yourself as rokushaku fundoshi, etchū fundoshi are also much more widely available, often called "classic pants" at various Japanese retailers. Etchū fundoshi also have a newfound popularity among female wearers (which will very likely be the subject of a future blog).
Etchū fundoshi also make a nice transition into fundoshi-wearing if any of the aspects of rokushaku fundoshi seem intimidating (the complexity of tying, the slight bulk of the twisted portions underneath clothing, the hygiene issues, or simply the more revealing outline). They are superbly comfortable, and especially ideal as summer underwear or sleepwear, or something light and comfy to wear while doing laundry. The ease with which they can be untied and shed is also an asset!
As far as public wear is concerned, etchū fundoshi also offer a little more coverage of the buttocks than rokushaku, however if you will be swimming or running you may prefer the security and support of rokushaku fundoshi, which are much less prone to "wardrobe malfunctions."
90% of the time when I reach for a fundoshi, it's rokushaku-style. I like the look, I like the feel, and I like to make my own fundoshi. However I've ordered a few pair of etchū fundoshi from www.jbox.com, and they've gone over quite well. I can't say enough how feather-light, comfortable, and barely-there they feel.
Here is an assortment of pictures of others enjoying ettchu fundoshi: