In some Japanese homes, there is a separate pair of slippers used only inside the toilet. Even if you are already wearing indoor slippers, you take them off at the door and change into the toilet slippers before going in.
The point is not simply to make your feet more comfortable. The toilet is often treated as a separate part of the home, and the slippers help keep what belongs there from being carried into the hallway or living areas.
That is why walking out of the toilet while still wearing the toilet slippers can feel quite unpleasant to some people. It is not as serious as walking into the house without taking off your outdoor shoes, but the feeling is somewhat similar. The toilet is still the toilet, and bringing something used there into the rest of the home can feel unhygienic.
This is similar to the way Japanese homes separate outdoors from indoors at the entrance. Outdoor shoes stay at the genkan, and in some homes there is another, smaller boundary around the toilet. Toilet slippers make that boundary easy to see and follow.
A toilet does not have to look dirty for this custom to make sense. Even if it is modern and the floor looks spotless, a household may still use separate slippers. The distinction is not based only on visible dirt. It is also about the simple feeling that something used in the toilet should stay in the toilet.
Not every Japanese household uses toilet slippers. People differ in how strongly they care about cleanliness and how separate they consider the toilet from the rest of the home. Some households do not use dedicated toilet slippers at all.
So if you visit someone’s home and see a pair of slippers inside the toilet, use them. And when you leave, make sure they stay there. Walking down the hallway in them can feel like more than simply wearing the wrong pair—it can feel as though you have carried something from the toilet into the rest of the house.
