Spas with solo travelers in Japan

Ibusuki, Kagoshima

Oceanfront outdoor onsen in Ibusuki where the two gender-assigned baths swap daily, with views of Mount Kaimon, the East China Sea, and Take-yama.

Noboribetsu, Hokkaido

A plain neighborhood bathhouse in Noboribetsu, Hokkaido, offering 100% source-fed hot spring water in two mineral varieties, about 10 minutes from the station.

Tokyo

Private-room head spa salon in Minami-Aoyama, Omotesando, offering 90- to 210-minute scalp treatments from roughly ¥24,750.

Ginzan Onsen, Yamagata

A no-frills communal bathhouse in Ginzan Onsen's Taisho-era hot spring street, open daily 8:30am-3:30pm except Wednesdays.