The Japanese seem obsessed with Lolitas. Schoolgirls seem to be the choice for representing Japan on the Internet. That obsession--which will get you arrested and publicly shamed in America--does present opportunity for us to learn about Japanese lingerie styles and history--at least a little. There is even distinction between the anime sexuality and child pornography. For more discussion see Loli in the Urban Dictionary.
This image presents a Loli in fundoshi.
Loli: (Noun - plural: loli or lolis); Sounds like "lowly", not "lolly".
"In Japan, panties are commonly depicted as adding a highly flirtatious, naughty element to a female's persona." cite
Pantsu: "The japanese word for "panties" (panties in a japanese accent) that since Chii from the series Chobits (CLAMP) has said, has spiraled into another form of slang for wannabe-asian otakus. Other examples of these incidents are phrases like 'kawaii desu' and 'konnichiwa.' 'Chii wears pantsu!' " cite (urban dictionary)
This seems to a recently developed slang term.
"Thongs are worn by slutty girls, regular pantsu is [sic] worn by innocent pure girls." this quote is from a forum where Japanese girls and their underwear is discussed. By the comments, the posters are as naive and lonely as the guys who post to the same type of forums in the US. However, it reveals something about the attitudes toward sexual purity--indeed, purity in everything--prevalent in Japan.
female characters bereft of pantsu, or in technical language, in a state of “nopan” (no pantsu).
the 褌 / fundoshi, or loincloth: "that most alluring of traditional undergarments, the 褌 / fundoshi, or loincloth, an item of apparel which manages to be at once ancient and rather modern in appearance.
Although fundoshi are usually thought of as exclusively male apparel, it appears that historically they have seen plenty of (normal) female use at various times, so the hungry depictions we see so often are not quite so fanciful as we might at first think.Even so, it seems traditionally no underwear as such was often worn by ladies."
"The makers of the women’s fundoshi have renamed their product pendre shorts
(パンドルショーツ), using the French verb for “hang” to give the underwear an feminine image." cite