Japanese Bath Etiquette

Most hotels in Japan, small and large, countryside or Tokyo, offer public bath areas, often fed by natural volcanic hot springs containing healing minerals. These are called onsen and are usually divided into male and female areas. [Differentiating between the Japanese characters for male and female is not difficult as the female one looks like a stool-quatting figure and the male kanji sports a head with a cross in it].
Tourists in Japan should definitely experience onsen as this is an integral part of the Japanese psyche and, in addition, performed properly a thorough onsen visit will make visitors about as clean as they ever will be. Japanese people enjoy the onsen ritual several times a month, if not daily, in addition to having a bath [still no soap in the bath!] or shower at home.
Step 1: if the hotel provides a robe, slippers and two towels [big and very small] in your room, wear the robe, bring the towels and wear the slippers up to the onsen entrance.

Step 2: Find a locker or basket, put everything in it except the little towel and if it's lockable, lock it. If not, don't worry, your chance of being robbed in Japan is about the same as being shredded by a Great White while taking a bath.
Step 3: Enter the steamy bath area with only the small towel which is partly used to protect your modesty if shy, and/or to wash more thoroughly with.
Under NO circumstances enter the bath itself [far left] without first washing yourself all over at one of the wash stations - visible through the steam on the right in the picture. There may be 10 or 20 wash stations, all provided with soap, shampoo and probably with a shower head, though traditionally Japanese squat on a wooden or plastic stool [rectangular wood in the picture], fill a small bucket with hot water [circular wood in the picture], then dunk it over the head and body, repeating the process; or use the shower head. When wet, soap and scrub the body with the small towel. Rinse and repeat if desired. Feel free to stand up to access the naughty bits.
Step 4: When totally rinsed and clean, enter one of the baths

All onsen in Japan will contain at least one hot bath, perhaps several baths, ranging from cold, to warm, indoor or outdoor [picture above, a rotenburo]. Move freely between the baths, but DO NOT put your now disgusting, foreign bacteria-filled towel into any bath. Many Japanese put the towels on their heads. If not, putting them beside the bath is acceptable.
If you wish to soap, wash and rinse and return to the bath again that is perfectly fine.
After soaking for as long as you wish there will probably be hairdryers, hair brushes and various Japanese body lotions in the dressing room. Enjoy!
The super-loo is now commonplace throughout Japan. Don't get freaked by the kanji [Japanese characters], these toilets are easy to understand, pleasant to use and more hygienic than using toilet paper. In the picture above the red button obviously means stop. The upper three blue buttons are the bottom washer, weak/medium/strong. The pink three buttons wash women's bits and the lower yellow threesome is the blow-dry feature, again weak/medium/strong [use medium if the kanji confuses you!]. Those are the essential controls though all toilets are a bit different. The unimportant brown buttons on the right are on/off so feel free to experiment with them, except for the lower right brown button that moves the blow dryer backwards and forwards to deal with big butts. The top two on/off brown buttons appear to give some kind of anus massage! Enjoy even more!