A ganbanyoku is a hot stone spa.
Picture a sauna where the heat emanates from a stone floor and you’ll be close. They are typically heated to somewhere between 40 and 50 degrees and are also less dry than a standard sauna.
The spa at Iyashitei is gender segregated. You are provided with loose clothing to wear, towels (one to lie on, another for the shower afterwards), and bottle of water by the proprietor before being shown to the changing rooms.
The recommended procedure is to spend 15 minutes lying on the hot stones before moving to the cool room for a few minutes before going back to repeat the cycle. Most people repeat this cycle 3 to 5 times before showering off the sweat and heading back into the world.
The type of stone is important, in this case it is tenshouseki stone from Takachiho in Kyushu, in other places granite or black silica. The stone is thought to emit negative ions, the same kind that occurs naturally around waterfalls and after a thunderstorm. The negative ions purportedly ‘purify’ the air by attracting positively charged floating particles such as mold spores, pollen, dust and even bacteria and viruses. This is claimed to produce benefits ranging from lowering blood pressure to improving skin to reducing illnesses.
Science is a way of thinking much more than it is a body of knowledge
I can’t testify to the scientific accuracy of such claims, but I can tell you that I found it to be a delightful experience. The hot stone against ones back feels not dissimilar to a massage, especially if you have the place to yourself and indulge in a few lower back stretches! The cool-down room has a beautiful view of the river and time passed alarmingly quickly as I reveled in the sensation of the hot stone.
It is definitely worth making the time to take the short walk across the river!