Takinoya’s onsen at the base of the building is sulfuric water or commonly known as hydrogen sulfide. The water is milky because it takes time for the hydrogen to with oxygen to dissolve in water.

“Onsen therapy has various medical effects,” says Yuko Agishi, a 71-year-old physician and honorary professor at Hokkaido University. “It is a type of alternative or complementary medicine, not directly curing the cause of the disease but treating the body as a whole; assisting in recuperation, rehabilitation and disease prevention.”

The onsen’s chemical makeup is one of the key elements of balneotherapy. According to the 1979 revision of the 1948 Onsen Law, nine types of onsen water are recognized as having proven medical benefits. These are nisankatanso-sen (spring water high in carbon dioxide), tansansuisoen-sen (hydrogen carbonate), enkabutsu-sen (chloride), ryusan-sen (sulfate), tetsu-sen (iron), io-sen (sulfur), sansei-sen (acidic), hoshano-sen (radioactive) and tanjun (spring water that lacks these attributes but has a temperature of over 24 degrees).

For example, sulfur onsen are quite effective for chronic articular rheumatism. Bathing in these various types of onsen is used to treat other illnesses, such as chronic skin diseases, diabetes, constipation, etc. And by partaking of this natural therapy instead of using conventional medication, it is believed that people can also strengthen their immune system and thus enhance their ability to heal themselves.