The receptacle is usually on a raised floor. The opening is rectangular with a sort of hood over one end.
Climb up on the raised floor and stand flat-footed astride the opening with your face towards the hood. Then bend down into a crouching or squatting position, making sure that your rear is over the opening and not protruding beyond it.
The position may not be comfortable but it is sanitary because no part of your body comes in direct contact with the fixings.
In the case of the male, he urinates by standing on the lower floor and aiming for the opening. Please aim carefully.
The most commonly heard word for toilet is ote-arai and to-ire (pronounced oh-tay-araee and toe-ee-ray). To ask for the washroom, simply say "toire doko?" (toilet, where?). The word for toilet easiest to remember is benjo, pronounced like two Western first names: ben-joe. However, priggish women object to the word just like some Western women avoid the word "toilet".
Public latrines are few and far between - and most of them are flithy. If nature calls when you are out in the streets, the best thing to do is to go into the nearest coffee shop or tea room and invest in the cheapest drink. It won't cost you much more than the tip you have to give to the lavatory attendant in many other countirs.