Medieval Japan discovered the healing powers of hot mineral springs (onsen) when hunters followed fleeing prey up to bubbling pools where the animals instinctively went to relieve their pain and tend their wounds. The healing properties of the waters, enriched by the surrounding volcanic soil, attracted tourists from all over the country. Elderly farmers, hunters, and fishermen soon discovered that the rich waters were effective for treating arthritic aches. It wasn't long before members of the various warrior clans began visiting favored hot springs to alleviate pain, heal wounds, recuperate, and replenish their energy.
There is little debate surrounding the therapeutic properties of Japanese onsen, and bathing rooms at some onsen still display lists of the many diseases and injuries that the mineral water can treat.
These days, Japanese onsen still attract large numbers of visitors, and thanks to modern plumbing, most Japanese homes have large bathtubs specially designed to simulate the onsen experience.
1,000 years after the onsen became such a cultural phenomenon in Japan, you can still see throngs of tourists, families, businessmen, and the elderly frequenting these revered hot springs in places like Kyushu and other regions where volcanic activity is still present. Some onsen even have mud pools or sulfur springs where bathers can receive rejuvenating mineral scrubs as they soak in hot, calming waters.