Yayoi's cousin Arima-san picked us up at the Kagoshima train station and drove us south to locations near Ibusuki. At Ibusuki itself which is a very touristy town, we entered a building next to the beach, picked up our ankle length yukatas and changed into these. Then we walked outside and down to the beach beneath a canopied structure.
Here we were asked to lie down with our heads on sandy pillows. Then sand was shoveled over our entire bodies except our towel wrapped heads. The heat from the geothermally heated water mixing with sea water beneath our bodies became warm enough that it almost caused burns. The recommended time was ten minutes, but the ideal was to stay until you began to sweat.
When you were tired of this you forced your way out of the sand and went back into the building to enjoy the sauna and/or the hot spring.
All sorts of medical claims were being made about the benefits of this treatment, such as turning your blood from black to a proper bright red.