Due to the COVID-19 pandemic, several ryokan hid their "Gensenfuro 13" from the public. However, you can buy the "Gensenfuro 13" bath salts online from the Yugawara Pharmacy. These salts precisely mimic the mineral ratio of Source #13, allowing you to recreate the brown, sulfuric water in your home bathtub.
If you are determined to find a working Gensenfuro 13, here is your roadmap: Gensenfuro 13
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Why does Gensenfuro 13 matter beyond the novelty? Authorization:
In Japanese aesthetics, there is the concept of wabi-sabi – beauty in imperfection. A Gensenfuro is raw. It is unpredictable. It might be too hot, too smelly (like sulfur or rotten eggs), or too metallic. Encryption:
The "13" represents the outsider. In a world of homogeneous, comfortable onsen (#1, #2, #3 are easy to manage), #13 is the wild card. To bathe in Gensenfuro 13 is to accept nature on nature's terms.
It is a statement: I do not want filtered, chlorinated, re-circulated water. I want the violence of the Earth’s crust pouring over my shoulders.
Finding Gensenfuro 13 is a pilgrimage for the ungen (hot spring maniac). It is the final stamp in the Yumeguri-cho (hot spring stamp book). Once you have bathed in the 13th source, all other baths feel like swimming pools.