Shichirida Onsen Shitanyu

Shitanyu is a communal bathhouse of Shichirida Onsen, located on the Kuju Highland in Taketa City, Oita Prefecture. Settlement here dates back to the Yayoi and Kofun periods, and the spring is mentioned in the Bungo no Kuni Fudoki, an eighth-century regional record. In later centuries it was used for cures by the local Kutami lords and by the feudal lords of the Oka domain during the Edo period.

The water is a carbon-dioxide-rich magnesium-sodium-calcium bicarbonate-sulfate-chloride spring, with a source temperature of about 37C and a pH of 6.3. Though colorless and clear, it contains an extraordinarily high concentration of dissolved carbon dioxide, and bathers are quickly covered head to toe in tiny effervescent bubbles. Renowned as one of Japan's most intensely carbonated baths, it is served unheated and undiluted, straight from the source.

The facility is a simple communal bath with gender-separated indoor pools only. Because the concentrated carbon dioxide gas can accumulate, the room is fitted with a ventilation fan. Admission is handled at the adjacent Konoha-no-yu: 800 yen for adults and 400 yen for children up to junior-high age. It is open 9:00 to 21:00 (last entry 20:00, shorter in winter) and closed on the second Tuesday of each month.