The character Katsushiro in a poster for the Akira Kurosawa film Seven Samurai. Katsushiro's fundoshi underwear is visible beneath his traditional armor.
The character Katsushiro in a poster for ‘Seven Samurai.’ His fundoshi is visible beneath his armor.

What are fundoshi?

Fundoshi are traditional Japanese underwear. There are a few different types of fundoshi, but all are made from a breathable, lightweight cotton gauze fabric called sarashi. Fundoshi have gone through a millenium of testing by Japanese people of all classes. Everyone—fishmongers, taiko drummers, yakuza, baseball players, and salarymen—wore fundoshi. The most famous example of fundoshi for people outside of Japan might be the Akira Kurosawa film Seven Samurai. If you’ve seen the movie, then you know it’s what samurai and their ninja apprentices wore beneath their armor.

How do you put on fundoshi?

You do not have to be an origami master to tie fundoshi.

Easy instructions, in three formats (written, illustrated, and videos) are available on the pages for rokushaku and etchū style fundoshi.

Are fundoshi what sumo wrestlers wear?

You’re probably thinking of the mawashi (廻し), though competitive sumo wrestlers usually wear fundoshi underneath. Mawashi is made from a thicker, canvas-like fabric, which is only washed twice: before you first use it, and the death of a wrestler’s shisho (the master of their sumo dojo).

A mawashi-wearing, heavyweight USA Sumo contender stretches out his haunches with his hands on his knees while up on his toes, at the Los Angeles Cherry Blossom Festival during an exhibition.
A heavyweight USA Sumo contender stretches at the annual Los Angeles Cherry Blossom Festival. Underneath their “mawashi” uniforms, made from thicker fabric (that is never washed due to superstition, only aired out), sumo wrestlers wear fundoshi.

Where can I wear fundoshi?

Everywhere.

People do it everyday: at work; during school; while working out at the gym. Remember: Millions of Japanese wore them daily, going back to (at least as far as historians know) the 8th century.

If you’re brand new (and/or shy), here are a few places to start:

In Bed.

Try fundoshi instead of, or underneath, your usual pajama bottoms. Lots of people say the comfort improves the quality of their sleep. It helps that the natural, cotton-mesh fabric is super-soft, and conforms like a cloud to sensitive muscles and body organs.

1931 US men's Olympic swimming team
The 1931 US National Men’s Swim Team wearing fundoshi in honor of their teammates, two actual brothers named Maiola and Manuella Kalili. The Kalili bros were Native Hawai’ians who literally grew up in fundoshi. They grew up to become the team’s stars, winning Olympic gold and silver medals in freestyle and backstroke. Photo: The International Swimming Hall of Fame.

Underwater.

Fundoshi are the original “swim trunk” or “speedo” of Japan.

While US swimmers and water polo players got support from swimming jockstraps starting in the early 1900s, Japanese surfers and swimmers had used fundoshi for over a thousand years. They’re both used for the same reason: they’re way more supportive than the loose mesh lining in board shorts and swim trunks.

A white fundoshi becomes basically invisible when it’s wet. However, there’s a simple solution if you’re not ready for that: Get a dark-colored fundoshi.

Tamotsu Yato, photographer. 1960s image of men participating in the ancient rite of Hadaka Matsuri (translation from Japanese: "Naked festival").
A Hadaka Matsuri from the 1960s shot by photographer Tamotsu Yato.

At festivals.

Hadaka Matsuri are yearly festivals held in hundred of towns around Japan. Usually in February but sometimes in the summer, hundreds of younger guys line up naked. A sensei (elder) tears pieces from large rolls of sarashi fabric and helps them put it on. There’s more to it than this, but the guys run through the town, wearing just fundoshi and maybe some tabi socks.

The ritual usually ends in a body of water, outside a temple, in the dark. If you make it all the way, good luck is supposed to follow you for the rest of the year.

Will fundoshi increase my sperm count?

According to doctors, yeah. Fundoshi’s natural cotton (or hemp or silk) fibers are healthier for skin than the petroleum-based elastic that makes up the waistbands of Western underwear. You also get to decide how tight your fundoshi is, so the production of sperm in your balls isn’t affected by tight underwear, or loose and non-supportive underwear.

The Japan Fundoshi Association explains the potential health benefits at length.

Is wearing fundoshi illegal in Japan?

After World War II, fundoshi and many other traditional clothes got banned by the US military overlords. If you wore fundoshi during that time you were technically breaking the law. As the saying goes, “some laws were made to be broken.”

In particular members of the yakuza never stopped and still wear fundoshi. And despite the law, non-mafiosos continued to stripped down to their fundoshi at places like the beach and public bathhouses (in Japanese they’re commonly known as onzen, or sento).

A vermillion red fundoshi with Japanese katakana and a star. The fundoshi is etchu-style, with a button for ease-of-use.
One of the red fundoshi that were worn by soldiers of the Imperial Army of Japan, during World War II.

Can fundoshi scare away sharks?

During World War II, Japanese military commanders told soldiers to strip off their fundoshi if they got caught in open water.

Why? Sharks are generally not going to come for you if they think you’re bigger than them. So an unfolded fundoshi, fully spread out and floating on top of the ocean, can give the appearance of a larger creature and could be a life saver.

You still have questions?

Ask us anything.

While tying a fundoshi is something most people pick up pretty quickly, here’s a tip if it’s your first time and you’re feeling frustrated: We recently added “how-to” videos for the etchu and rokushaku style fundoshi, and we’re working on better quality ones right now.

Take a look at the loads of tutorials made by Tanukichi the Fundoshi YouTuber. The dude has literally hundreds of useful tutorials that you can speed up, slow down, and pause on any steps you might have trouble with.

Most of our knowledge is from Japanese sources, and there aren’t a lot of English histories about this centuries old garment. Recommended for those who want to learn more: Fundoshiphile.