The public restroom is arguably a symbolic microcosm of the linguistic changes in Japan today. Visitors to Japan come with various purposes, but they all come in contact with public restrooms. The restroom is one of the first places an entering tourist will visit, and one of the last places they will see before leaving the country.

However, development of high-tech restroom and sanitary equipment in the Japanese public lavatory has progressed with astonishing speed in the last half century, due to technological advances and competition between major manufacturing companies. The number of buttons, levers, sensors and other items to push, pull or pass a hand over has correspondingly increased in recent years, presenting great confusion and requiring signage that never before existed. Therefore, the ladies room is an ideal place to study the nationwide development of multilingual landscapes in a controlled environment.

Why is multilingual information necessary for a physical function that exists everywhere around the world? The figure shows two major reasons for confusion:

 (R1) differences in customs or manner of using the same or similar facilities and 
 (R2) encounters with previously completely unknown equipment. 

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Different customs (R1)include whether to close the door, whether to knock on the door, and whether to be embarrassed about bodily noises. Unknown equipment (R2) comprises the otohime button, emergency button, washlet and bidet controls, etc.

Depending on the home environment, some aspects could be R1 for some tourists and R2 for others. The western toilet is a good example. Look at the sign below. (commentary?)

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The flush mechanism (the most important one!) is especially confusing. It can look like a button, sensor or lever, and can be located on the wall, side panel, on top or in back of the toilet. It can also be nowhere if the toilet is self-flushing. Therefore it often needs explanation.

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The emergency button, if pushed, always causes trouble for the building manager. Therefore, this button always has the most international signage associated with it.

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On the other hand, the otohime or flushing sound button is considered to be important "for Japanese only" and is rarely translated into other languages. This creates trouble for people who accidentally push it instead of the flush button.

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What is better ways to make toilets international? Pictograms are helpful, as in this picture:

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Simplification is also a good method, as follows:

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Finally, one of the best signs in the Japanese public restroom says "Thank you for keeping the restroom clean." It is short, positive and polite.

For further reading: Yoneoka and Saito 2017