The whole territory of Japan is dotted with countless hot springs resorts, with secluded ponds and medicinal baths, whose waters are highly regarded for the beneficial effects in pain treatment and skin care.
The term “medicinal bath” can either designate a pool of thermal water containing Chinese herbs, or a bath whose healing properties have been demonstrated. Thermal baths are popular among all ages, because their waters never cool and have the effect of promoting blood circulation. In those very waters, warlords would heal their wounds in the past.
According to the Hot Spring Efficacy List, compiled during the Edo Period, there are three major locations for medicinal baths: Kusatsu in Gunma prefecture, Arima in Hamamatsu prefecture and Matsunoyama in Niigata prefecture.
Here is a list of hot spring resorts known for their efficacy.
Kusatsu Onsen
As one of the three most renowned medicinal bath locations, Kusatsu Onsen is a collection of 18 communal baths, freely accessible, situated at an elevation of 1,200m. With a pH value of 2.1, its acidic waters (the most acidic in Japan) have bactericidal properties that are effective in treating chronic skin diseases, neuralgia, and abrasions. The Yubatake, one of the biggest hot springs and the symbol of the town, is surrounded by 100 name plates of notable persons that visited Kusatsu.
https://www.kusatsu-onsen.ne.jp
Gero Onsen
Gero Onsen is located along the Hida River in the Northern Alps (also known as the Hida Mountains), and one of the reasons for its popularity is its healing properties. The onsen is closely related to Oda Nobunaga, the powerful Japanese feudal lord who gained control over most of Honshū in the 16th century. He is said to have sojourned at Gero Onsen in 1578. With a pH value of 9.2, its highly alkaline waters are reputed to have beneficial effects on the skin as well as to ease muscle pain and cold sensitivity.
https://www.gero-spa.com