The healing red water

Seki Onsen is called one of the three great onsen of Echigo (the old name for Niigata). The water has a high concentration of iron, resulting in its reddish brown color and a slightly metallic (but not unpleasant) odor. Hot springs with a high level of iron are actually quite rare in Japan. The water also contains sodium chloride and bicarbonate, so, to put it simply, it’s rich in iron, salt and baking soda. The salt provides a moisturizing and heat retention effect, while the baking soda is very cleansing. The result is something like the combination of shampoo and conditioner, and is an almost ideal beauty bath.

Legend says that Seki Onsen was discovered by famous eight-century Buddhist priest Kobo Daishi. It seems to have been a base for mountain worship activities, with area landmarks, temples and other spots still known for their connection with these practices. It later was the secret bathing spot for daimyo Uesugi Kenshin, one of the great leaders of the 16th-century Warring States period and who worshipped Mt. Myoko. The remnants of a small castle and an area where Uesugi family graves are located can be found here.

Seki Onsen opened as a full-fledged facility in 1727, and was operated by what is today Sekiyama Shrine, at the base of the mountain below Seki. It was at this time that it became known as one of the three great onsen of Echigo. It has since been ranked in several modern national onsen listings for the efficacy of the water.

In the past, a custom known as Tomeyu meant that people would not enter the bath for two weeks in May and June. It was believed that the gods and Buddhas of the mountain, along with insects and animals, would come down from the hills to bath. This was a truly frightening sight, so people would not go out at all, but simply wait for the spirits and creatures to return to the high country.

All of Seki Onsen's inns use this natural spring water. Although it is known for its reddish color as it emerges from the earth, in fact there is no color in the baths. This is because the water is very fresh and has not oxidized. If the water sits for an extended period, though, it will turn a rusty red.