OK so for anyone that's travelled to Japan you know what I'm talking about.

They're devices that are a textbook example of excessive featuritis.

But I want to use something other than the flush knob before leaving Japan. What is a feature that has the following characteristics:

    Common to most Japanese toilets.

    Hard to get wrong - won't create a mess or damage the toilet.

    Simple to comprehend - more likely to involve romaji or kana or simple kanji or pictures.