I've traveled to Asia before, so Asian-style plumbing was no surprise to me. I remain astonished at the number of western women who either avoid going to Asia altogether out of fear of the toilets, or hide out in western-style hotels and shopping centers. Listen to me, ladies! Using Asian-style toilets is not that big a deal.
In Japan, all toilets are very clean, with proper arrangements for your privacy and washing up after. That said, the item in question, the slit toilet, takes a bit of getting used to. In Japan, all toilets are made of china or some manmade material. Every one I saw or used had a flushing device. Nearly every 'restroom' had toilet paper in each stall. More on that later. So you need to settle yourself to the idea that you aren't going to spend all your touring time waiting in line for the few western-style toilets, which are usually in the major tourist areas, roadside rest areas, hotels and shopping centers. Face the Japanese fixture head on, so to speak, and get used to using it. The only possible excuse for not doing so is being physically impaired so that you can't, just can't. One Japanese woman gave me the advice that it's 'bad luck to fall in'.
Guidebooks give you a little idea on how to approach this act of nature. Here are the basics. Make sure you have a package of tissue in purse or pocket in case there is none available. You must rely on your own supply for drying your hands in most situations. After you locate the women's facility, which is very easy to do these days with generally understood international signs, either find one that is open for use or wait in front of one that is busy. Don't line up at the door. That's not how it is done in Japan.
If you see several women in the room, you are in the correct place! Don't be surprised if there is a lot of talking between stalls. Japanese women aren't embarrassed about these matters. Open the door to the stall and seek out the hook or shelf for your purse and etc. Face the flusher. Repeat, face the flusher. Adjust your clothing so that your bottom is bare and squat down over the fixture. Sometimes there is something to hang on to. On trains, there are handles. Bend your knees and squat as low as you can. Past experience in ballet or gymnastics is helpful, but nearly anyone can manage the task. More than once, a Japanese woman gave me a kind smile for using 'her' type of toilet. If you can manage this on the bullet train, you are a champion!
When finished, dry yourself off with either provided toilet tissue or your own supply. Put the used tissue into the basket at hand. Do not attempt to flush it down the toilet!!! No! Step away from the fixture, adjust your clothing and then flush. Gather all your belongings and go to the area where you wash hands. Wash your hands very well. It is a tradition in Japan to do so. You would be amazed how many western women skip this step and cause discomfort for the Japanese women. Use your own tissue to dry your hands and put it either in a wastebasket (very hard to find in these days of terror worries) or into your pocket or purse for later disposal. Do not be surprised if an attendant is continually cleaning the toilets.
Gentlemen. Obviously you have a much easier time for most matters, but you will need to carry your own tissue for hand drying. Also, you will have to get used to having women cleaning the toilets while you are in the area. This caused my husband much embarrassment until one cleaning lady told him in English to 'just go ahead and pee'. After he got over the shock of that comment, he did.
Many Japanese advertisers hand out packets of tissue on shopping streets (sometimes with sexy pictures), so make sure you have some in pocket. Sooner or later you will need it. It's not just for your nose.
Most of the time you can find western-style toilets, usually of the TOTO brand. Very fancy, but you need to be able to use what you encounter.
Now, about Japanese bathtubs - and this is hardcore data. Japanese people are extremely picky about the use and care of bathtubs, even in your own hotel room. In most of our hotels, we had a familiar-looking bathtub and shower combination; so I felt free to wash my hair in the shower. However, in situations where we only had a bathtub, you absolutely do not put any sort of soap, bath oil, shampoo, etc. into the tub.
You will find a drain in the floor, a tiny stool to sit on, and a handheld shower device. You are expected to wash and rinse yourself (hair and all) while sitting on the little stool. Remember: do NOT put any sort of soap into the deep Japanese bathtub. It will take the person who cleans your room a great deal of time and effort to remove the residue.
My first attempt at washing myself while sitting on the little stool (bamboo at that) was in Singapore. I ended up sprawled on the floor. Practice has perfected my technique, but not to the point where I enjoy the process. Once entirely clean and rinsed of all soap, you ease yourself into the bath, which is full of hot, sometimes extremely hot, water.
In public bathhouses, you go through the washing, soaping, rinsing process entirely before going in to the public bathing area. Men and woman are usually separated and are naked. Yes, folks, entirely naked. Naked with strangers. Flab, scars and all exposed and no one worries about it. Women with long hair are expected to put it up with a rubber band, usually provided. You can wear a shower cap.
When in a public bathing facility, you will find shoes outside the toilet area that say in English TOILET SHOES. You put these on when going into the toilet and exchange them for your own bathing shoes when leaving the area. Do not wear your toilet shoes elsewhere in the facility. You will be scorned for doing so. Do not walk around barefoot. The Japanese are sensitive to the idea that only clean feet should go into the bathtub.
Every hotel I stayed in provided bathing shoes and kimono and some, few towels. Small towels. Big bath sheets are not the fancy in Japan. You won't have enough towels, so try to put them where they will dry.
Hot water for bathing in Japan is very hot. Be very careful! Fill your tub carefully, as you don't want to get burned. Japanese people bathe at 110 degrees F. Very hot to us!
Please don't be afraid of the toilets!