Every group that travels to Japan with us has the same first evening. Before supper in the inn, the leader explains how a Japanese bath works, and for about ten minutes nobody says anything.
Wash first, then soak
You wash at a low tap, sitting on a small stool, and rinse off every trace of soap before you step into the shared water. The bath is for sitting in, not for washing. The small towel stays out of the water; most people fold it on their head.
No swimwear
Shared baths are separated by sex, and swimwear is not worn. This is the part that worries people most, and it is the part they stop noticing first. Nobody looks at anyone. If you prefer, every inn on our routes has a private bath that can be booked for the group or for a couple.
Short, then shorter
Some of the water in Kyushu comes out of the ground above 40 degrees. Five or ten minutes is plenty, followed by a rest on a bench and a glass of water. By the third evening most travellers have their own routine, and by the last one they want to know whether there is a bath at the airport.