Hi! I’ve had a few questions about this so I thought I would just make a post so I don’t have to type the same thing over and over.
I will also add to and edit this post as I go.
I have written a blog post for those with IBS in Japan and many of the tips are the same as the main concern is, of course, being able to find a restroom easily.
Here is a hack for an easy way to always know where your closest bathroom in Japan is at all times.
My tip is to download an app called Mamapapamap.
This app has been designed for breastfeeding mothers and parents with small children – to show places to change baby, heat up food and also shows where to find boiling water to make formula or heat up baby food.
But is is also great for using to help you find toilets as ADULT toilets are also found in all of these places. And, of course, so handy if you need a toilet quickly for a toddler. The app is in English and is updated often. Highly recommend.
Bring around with you
Extra nappies and changes of clothing (as you would at home.) If you are stuck for clothing options to buy here are stores in Japan that I use often for children’s clothing and here are a list of Japanese brands of kids’ clothing too.
Can we bring a port-a-potty / training potty around with us in Japan? Will it be poorly received?
Yes – bring it – if you must… but keep it in your hotel room. Don’t bring it around with you. It isn’t appropriate and isn’t the “done thing” in Japan.
If your trip to Japan is short and using a potty all the time is part of your routine – then I recommend putting toilet training on hold for your holiday OR using diapers/nappies as if they are underwear (or underwear underneath the nappy) and trying to keep them dry for as much as you can.
See here for where to buy diapers easily in Tokyo
Big shopping malls, zoos and some sightseeing spots in Japan have children’s restrooms
Little tiny toilets and the women’s bathrooms also often have a little urinal for little boys to use.
Toilets on trains & buses
Bullet trains – yes. Express trains- yes (but not as many options.) The Airport Limousine Bus from the airport? Yes.
For kids with good aim or for long car trips – did you know that you can also buy a portable toilet at the drugstores or on Amazon in Japan?
It can be used by adults or children for car trips or just to have with you for emergency situations. It can also be handy when toilet training children in Japan. 
