My first onsen experience was in Taiwan. My friends and I went on condition that swim wear was allowed. My second time was a year later with Mr Mode, also in Taiwan, and swim wear was definitely encouraged since it was a mix gender public onsen.
When I heard that we had to go completely naked for an authentic Japanese onsen at Ryugujo Spa in hotel Mikazuki, I firmly said ‘no, no, no’. I mean, if you grew up in a completely naked onsen culture, you’d be open about exposing your bits to strangers and friends alike. But most Singaporeans didn’t grow up that way and my previous onsen experiences didn’t prepare me enough for it!
But an hour later I found myself walking down the hall clothed in a thin, floral, pink Yukata, my heart thumping in anxiety, threatening to shoot out of my birthday suit. We reached our lockers, shed the Yukata, and agreed to look at one another ‘neck up’ hahaha. 😆 Then we commenced the walk of shame, also known as the short distance from lockers to shower area to pool, but which felt like eternity.
The main reason why swimwear is not allowed in a pure onsen is because the goal is to keep the water as clean as possible. Another reason I heard is that the temperatures can be so high they can melt certain kinds of fabric.