Gensenfuro 13 May 2026

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.

Embedded in the headrest are 13 pressure sensors (one for each generation). When you recline, the Gensenfuro 13 detects muscle tension patterns. It then subtly adjusts the direction of two micro-jets to target your specific knots, similar to a hydrotherapy massage. Gensenfuro 13

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In the folklore of onsen towns like Tsuchiyu (Fukushima) or Shiobara (Tochigi), local springs are often catalogued by volume and temperature. The number 13 is notoriously rare. Due to the COVID-19 pandemic, several ryokan hid

Why? Superstition.

In many traditional Japanese inns (ryokan), there is no room number 13. Elevators skip the 13th floor. This is due to shini-gachi (a variation of tetraphobia), where shi (death) sounds like the number four, but 13 combines that death-adjacent feeling with the Western "unlucky 13." Embedded in the headrest are 13 pressure sensors

However, in the world of geothermal engineering, Gensenfuro 13 emerged as an outlier. According to geothermal logs from the Showa Era (specifically 1956 and 1973), Source #13 in several prefectures was the "wild source."

The legend says that most hotel owners avoided tapping Source #13 because it was "cursed" – prone to sudden brown outbursts of arashi-yu (storm water) or overly aggressive gas emissions. Only the most adventurous yuzan (bath masters) dared to use it.