A Meiji-era inn at the entrance to the Jigokudani Monkey Park, famous worldwide for wild macaques that climb into its rotenburo in winter. Day bathing is only 12:00–15:00, so most visitors combine it with the monkey park. It's a 30-minute mountain trail from Shibu Onsen — wear grippy shoes in winter.
The centerpiece of Nozawa's 13 public baths, a traditional bathhouse in the middle of the village. Local 'yunakama' associations have cleaned it daily since the Edo period; payment is a donation in the box at the door. Two pools, hot and 'mild' — though even the mild one exceeds 42°C. Adding cold water is bad manners: rinse first, then keep soaks short. No soap or shampoo.
The signature inn of Shirahone, famous for milky-white water. Its highlight is a large mixed-gender open-air bath — the water is so opaque that women find it comfortable. Day use at midday only.
One minute from the Yudanaka station gate: a free-flowing day bath with two bathrooms (each with an open-air tub) that swap monthly. The lounge overlooks the platform — perfect while waiting for the train back from the snow-monkey park.
Of Shibu's nine communal baths along the cobbled street, No. 9 'Ō-yu' is the only one open to non-guests. Hot rusty-brown water plus a steam room fed by the source; a footbath on the roof. Buy a ¥800 ticket at the tourist office or nearby inns and have the door unlocked for you.
In Nozawa, where 13 outer baths are free (donation), this is the only paid day facility with showers, shampoo and an open-air bath. A handsome building with a curved gable, hot and mild indoor pools and a stone outdoor bath — the fallback when the outer baths are too hot or you want a proper wash.
Right at the Shirahone bus stop, gender-separated public open-air pools built against the gorge cliff. Milky bicarbonate water for ¥700; no washing area, pure rustic soaking. Closed late Nov–late Apr and Tuesdays. Handy before or after Awa-no-yu's short day-use window.
One of the three public 'outer baths' of Bessho Onsen near Ueda, the spa village nicknamed 'Kamakura of Shinshū'. Ishiyu is famed as the hidden bath of warrior Sanada Yukimura in Ikenami Shōtarō's novel Sanada Taiheiki; its tub is built around natural bedrock, filled free-flowing with faintly sulphurous, mildly alkaline water. Open 6:30–21:30 (last entry 21:00), closed Tuesdays, a modest ¥300 with free lockable lockers. Pair it with the other two — Ōyu (closed 1st & 3rd Wed) and Daishiyu (closed 1st & 3rd Thu) — plus Kitamuki Kannon temple and the National Treasure octagonal pagoda of Anrakuji, all on foot. Ten minutes' walk from Bessho-Onsen Station on the Ueda Dentetsu line.
In Asama Onsen, Matsumoto's spa hinterland, this day-use bath occupies the house of the hereditary bath-keepers who guarded the lords' private 'Goten-yu' for 400 years, since castle lord Ishikawa Kazumasa. Old garden trees and displays on the bath-keepers' history give the place the feel of a heritage site; the clear, mildly alkaline simple spring is fine-textured on the skin. Besides the main hall there is an open-air bath in a separate wing and a rest room, and many visitors come straight from Matsumoto Castle. Open 9:00–21:00 (last entry 20:00), closed Mondays (or the next day after a holiday), ¥900. About 20 minutes by bus from Matsumoto Station to Asama-Onsen Bunka Center-mae, then 10 minutes on foot.
A Western-style bathhouse on the shore of Lake Suwa, built in 1928 by the Katakura silk dynasty for the welfare of local residents and now an Important Cultural Property. Its famous Sennin-buro is a marble pool 1.1 m deep — you bathe standing, pebbles underfoot, surrounded by stained glass and sculpture — named for the hundred people it can hold at once. It uses Kamisuwa's spring water and also has a sauna and jet bath. Adults ¥750, open 10:00–20:00 (last entry 19:30), closed 2nd and 4th Tuesdays. The 2nd-floor rest room (until 19:00) and canteen (11:00–15:00) are open to bathers, and tours of the hall building are offered. Eight minutes on foot from Kami-Suwa Station, handy for Suwa Taisha shrine and Takashima Castle.