In ancient China, rulers used hot springs as a place of relaxation. The Emperor Xuan Zong had hot springs installed in a Palace (Hua Qing Palace) with a pond inside. He was used to spend enjoyable times in this area accompanying Yang Guifei. The benefits of hot spring were well known in ancient China and have been described in many books, such as Onsenfu by the Han dynasty scientist Zhang Heng. Of these books, Honzoukoumoku written by Li Shizhen is the most famous, in which hot spring (boiling) water is described as that which gushes out of the surface of the earth with a smell of sulfur.
In Japan during the Edo period, Kaibara Ekiken described considerations for bathing in hot springs in a book named Youjoukun. Later, Kampo doctor Goto Konzan recommended bathing in hot springs of higher temperature. His disciple Kagawa Shuutoku referred to ways of hot spring bathing in the book Ippondouyakusen.
Since balneotherapy can impart influences on the pathological states of “Ki, Ketsu, Sui", it seems that couse of hot spring and Kampo medicine does give rise to beneficial effects.