I went to one of Japan’s best hotsprings—Kusatsu Onsen in Gunma—a couple of weeks ago and at the ryokan where the group of us put up, the owner oriented us on the general layout of the somewhat hidden accommodation (we actually went the wrong direction up before being led back down again after deciding to give them a call).
When the lady was telling us where the bathhouse was, she also mentioned that there is no soap. So, being the ignoramus we were, we started complaining among ourselves on how an onsen accommodation can provide no soap. One of my friend decided to purchase one from the nearby convenience store to share.
At night, when I went into the bath area, there wasn’t anyone in there. I sat myself by one of the shower heads and started washing myself. As I began washing my body with soap my friend bought, another man came in. He grabbed the nearest shower head, wet himself and headed straight for the onsen. In my heart, I was wondering if I should lend it to him if he were to ask for soap, but he didn’t, which surprised me. I continued washing myself like an idiot and when I felt super clean, I headed for the baths.
Some 10-15 minutes later, I was done (you are not supposed to sit in the onsen of Kusatsu for too long because of its high acidity. They even have an hourglass timer for you). As I was drying myself in the changing area, I noticed a notice on the wall. It listed a list of things to note before getting in. I read the notice and one of the points read, “due to high acidity of the onsen, do not use soap.”
Now it made sense why they don’t provide soap. You’re not supposed to use them in the first place. One of the reasons is that, the alkalinity of the soap and acidity of the water makes it hard to lather (because if you still remember your Chemistry class, acid and alkaline neutralizes), even though I didn’t have trouble doing that. But more so, the high acidity and temperature of the onsen actually kills all the bacteria, so there is no need for soap and the bath water will not get dirty. Note that this is only true of Kusatsu. Please use soap at other onsen areas and public bathhouses.
They do provide shampoo though. Hmm…
On a separate note, my friend decided to fly his drone in the room even though we told him not to. In the end, he tore the paper on the wooden lattice doors in the room and we had to split the bill to pay for the damage. WTF…