You need a fistful of operating instructions which are either on an instrument panel beside the loo, or in some cases the buttons and instructions are on the wall in front in front of the loo.
The heated seat (as I mentioned before) is the first thing you notice. The heat can be dialled up or down or turned off altogether. Then there is the 'bidet' section; front washing, rear washing, temperature variation, variable water flow & nozzle cleaning?? Oh and the pipes are emptied when you push the button so that by the time the water reaches you it is warm. I almost forgot about the music; waterfall noise or other musical sounds, god forbid you should hear anyone else. They seem to have thought of everything, and all this applies to public loos also. I wear glasses for reading but do not need them elsewhere, so it took me a wee while (sorry no pun intended) of peering at symbols and Japanese writing before I actually worked out what all the buttons were for. There is a trap: some toirets do not flush automatically and the flush button is sometimes cunningly disguised as a piece of wall or plumbing or something innocuous & you can easily spend 5 minutes hunting for it. And you do not dare leave until you find it.
I feel sorry for Japanese visitors to New Zealand, they are in for a big shock.