Sooner or later, when you visit Japan, you will encounter the Washlet. This is pretty much the standard toilet in most domestic premises and in half-decent restaurants and hotels. It looks, in the main, like an ordinary toilet but it has a set of electronic controls associated with it. Sometimes the controls will be mounted separately on an adjacent wall or as in the above they will be mounted on a arm that is fixed the main body of the toilet.
The Washlet has a heated seat, often these are heated all year round, but you probably wont notice unless it is cold outside. The Japanese have become so accustomed to having warm toilet seats that this is the thing they mention as being one of the big differences with other countries, when they visit.
The controls do not always have an English translation, but the symbols are always the same. The Rear button, which looks like a butt being sprayed with water is indeed that. The text says Oi Shi Ri which is “Bottom”. Press this button and you will get a shower spray on your derriere. You can adjust the spray pressure if you chose. Some models will also have a control to allow you alter the position of the spray, the one above is the basic model and doesn’t have it. The button to the right of that, which has an icon that looks like a woman sitting on a shower is the bidet function. Again the pressure and sometime direction can be altered. The spray will continue until you press the stop button. The other button on this above Washlet, with the musical notes icon, will play a sound, sometimes music, sometimes a noise that sounds like a toilet being flushed will be played. There is a volume control for this function. The purpose of this is to give the user some privacy.
Some of the more fancy Washlets will have controls to raise the toilet lid, some will automatically open the lid when a presence is detected. This particular Washlet has a manual flush control but some will have automatic flush control.
You can use the Washlet without using the electronic functions and my advice would be to only use the functions if you are sure about how they work. Don’t just randomly press the buttons, you could end up wet in places you are not expecting to get wet.