Ryujo Onsen

Ryujo Onsen — Dragon Castle Hot Spring — is a historic public bathing facility in Okazaki, Aichi prefecture, Japan, originally established in 1925 in the Taisho era as a traditional sento (public bath) that served the working-class residential district of Tamachi for nearly a century, taking its evocative name from the nearby Okazaki Castle — known as Ryujo or Dragon Castle — the birthplace of Tokugawa Ieyasu, the warlord who unified Japan in 1603 and founded the Edo shogunate that ruled for 265 years. After closing for extended renovation, the facility reopened in 2024 as 'Ryujo Sauna,' continuing the community bathing tradition in a updated format that reflects the twenty-first century Japanese sauna renaissance while maintaining the connection to the neighborhood's historical bathing heritage in the shadow of the castle where Tokugawa Ieyasu was born. The facility draws visitors who combine the thermal bathing experience with exploration of Okazaki's Tokugawa heritage, making the hot spring and sauna a complement to one of central Japan's most historically significant castle cities.