A visit to the onsen is intrinsic with life in Japan; without it… it wouldn’t be life in Japan. It’s easy to overcomplicate onsen etiquette so we’re going to make it easy for you. The rules can vary, but rest assured the basics remain the same.
Bring your birthday suit. Clothes go into a little basket or locker provided in the change room once you enter. Be neat. You are in Japan.
The best shower. Ever. Keeping the onsen water clean is a big deal so washing thoroughly before you enter is a must. And actually, this can be the best part: sit down (so you don’t splash your neighbour), lather up, wash your hair, condition, exfoliate, have a shave… all from the comfort of your little plastic stool and personal mirror. Japanese people are serious about cleanliness and you will notice locals doing the same, so indulge a little, it’s like a day spa. Well… a naked one anyway.
Resort onsens will have an intriguing array of shampoos, conditioners, soaps and body lotions on offer. Bring your own or have fun trying out the quirky Japanese ones. Traditional onsens may have only shampoo or body soap, so bring your own potions if you want some extra pampering.
Towels. In the onsen you will rarely see anyone walking around in a towel, but if you want to keep covered up before you hop into the water, you can. Men are sometimes issued with a ‘modesty towel’. Just pop it on your head once you are in, and be sure that towelling never touches the water.
Tattoos are a little taboo. Traditionally, people with tattoos aren’t allowed in onsens because of an age-old association to organised crime and the Yakuza. Times are a-changing though and more onsens are making exceptions. Ski towns and other tourist areas do tend to relax the rules, so if you’re sporting ink it shouldn’t be a problem.
Hair up. It’s all about keeping the water clean. Do not dunk your head and do not let your hair fall into the water. For all those men with long hair; it’s man bun time.
Not an après bar. Traditionally, onsens do not allow alcohol but as Japan moves with the times this rule is often relaxed. Many onsens have vending machines with alcohol and soft drinks so it’s okay to take in a relaxing beverage. Most people enjoy a little warm sake, a cold beer or an ice cream after the onsen in the chill-out room.
Watch and learn. Just remember, gaijin (foreigners) can inadvertently offend Japanese people in any of a thousand different ways, at any moment. Japanese people won’t confront you about it because they are too polite and it’s seen as disrespectful. But as a traveller; when in doubt, observe how the locals act, and act accordingly.
(Link) Not all onsen were created equally; so you’re feeling ready to give it a go, check out the 3 Types of Onsen in Japanese Ski Towns.