Sashiki Onsen — Enjin-no-yu 天然温泉さしきの猿人の湯
Water that is neither filtered, heated nor diluted: from the second floor you can see the Pacific.
The onsen is in the Yuinchi Hotel Nanjo, in the south of the main island, but it is also open to the public for day visits. Nanjo is the same city as Sefa-utaki and the Mabuni peace park.
Okinawa
Shita Oyakebaru, Shita Oyakebaru, Shinzato bira
https://theanimetrip.com/luoghi/onsen-sashiki-no-enjin-no-yu