After staying at a hot spring inn with my family, we were charged a "bath tax" for the number of guests. I did not use the hot spring.

In Japan, when you use a hot spring, you are subject to a "bath tax". This tax is collected and used by the local government to promote tourism. In general, it is assumed that guests of hot spring inns use the onsen every day, so the onsen tax is charged for the number of days you stay multiplied by the number of people staying at the inn. If you do not use the hot spring during your stay at a hot spring inn due to illness or injury, please consult with the inn staff. The standard amount of tax is 150 yen per person per day, but it varies from municipality to municipality.