Outdoor onsen (rotenburo) in Gunma

Kusatsu · An outdoor bath is normally part of the facility, but the men's-side outdoor bath and graduated 'awase-yu' were under roughly a month of construction starting mid-August 2026 (women's side unaffected) — worth checking current status before visiting.

Takasaki · Has an outdoor bath area with a large rotenburo and outdoor rest spaces.

Annaka · An outdoor bath is widely confirmed.

Numata · Open-air rotenburo with river-terrace and mountain views is the facility's main draw.

Ota · Multiple varied outdoor baths (roughly 4-5 types) including jet baths and a carbonated bath.

Shibukawa · One outdoor bath alongside two indoor tubs.

Numata · Multiple reviewers describe two outdoor baths of different sizes.

Shibukawa · A sky-view outdoor bath on the upper floor with mountain scenery is a highlighted feature.

Maebashi · A substantial outdoor bath area with multiple tubs and an outdoor rest zone is a repeated highlight.

Maebashi · One outdoor bath is present.

Minakami · Extensive outdoor bathing area overlooking the reservoir, widely praised.

Katashina · Multiple outdoor baths with mountain views are the facility's main draw.

Shibukawa · An outdoor bath is a major highlight, repeatedly praised for its view over the Shibukawa area.

Shibukawa · An outdoor bath with a garden seating area is available.

Maebashi · There is a separate outdoor bath area alongside the indoor baths.

Minakami · An outdoor rotenburo by the river is the facility's most frequently praised feature.

Takasaki · An outdoor bath exists (reviewers count just one); opinions vary on its temperature and view.

Isesaki · Has an outdoor bath area with a hot spring-fed tub plus a carbonated tub, described positively across four reviews.

Isesaki · Multiple outdoor baths including a source-fed reclining bath and a hot cypress (hinoki) bath.

Takasaki · Multiple outdoor baths including a mineral-crusted rock bath are widely praised.

Ota · Multiple reviewers describe outdoor cypress, stone and tsubo baths.

Tomioka · The outdoor bath has a scenic view and reopened around June 2026 after an extended water-shortage closure that ran through spring 2026 — worth confirming it is currently open before visiting.

Nakanojo · An outdoor bath alongside the indoor one is repeatedly described, overlooking the Shima river.

Higashiagatsuma · Multiple reviewers describe both an indoor and outdoor bath.

Minakami · A large outdoor bath facing the river/gorge, a highlight of the facility.

Annaka · An outdoor bath is available alongside the indoor tubs.

Maebashi · Has a spacious outdoor bath, also fed by the natural spring.

Yoshioka · A substantial outdoor bath area with multiple tub types.

Naganohara · A small outdoor bath alongside the indoor bath, confirmed repeatedly.

Maebashi · There is an outdoor bath area in addition to the indoor tubs.

Isesaki · Multiple reviewers confirm an outdoor bath area, with one counting four separate outdoor tubs.

Yoshioka · A spacious, open outdoor bath area is a highlight, mentioned across many reviews.

Maebashi · A roofed, open-air-style outdoor bath exists, though one reviewer called it plain-looking.

Kiryu · A small outdoor bath (4-person capacity) exists, but one reviewer reports the larger outdoor bath was closed for maintenance for an extended period.

Tsumagoi · An outdoor bath exists, but it was closed for an extended stretch (roughly January through March 2026, apparently for heating-cost/maintenance reasons) before reopening by April 2026 — worth checking current status before a visit.

Takasaki · Two to three outdoor baths including a carbonated-spring tub and a kakenagashi spring tub.

Minakami · A small outdoor bath is part of the multiple tubs on offer.

Shibukawa · There is a small rock-style outdoor bath alongside the indoor tub.

Kawaba · Widely confirmed indoor and outdoor bath.

Takayama · An outdoor bath is present, generally described as lukewarm.

Ueno · An outdoor bath overlooking the Kannagawa river is the facility's main draw.

Katashina · Large outdoor baths (split into two sections) are the facility's signature feature; multiple reviewers also note slippery moss on the floor and insects in the water.

Maebashi · A sizable outdoor bath area (rock bath plus a lukewarm tub) is consistently mentioned.

Numata · An outdoor bath is confirmed by many reviewers as a highlight.

Numata · An outdoor bath area (three tubs, though one waterfall/uchidase bath is sometimes out of order) is a major highlight for most, though one reviewer felt it's more a roofed pavilion without open sky than a true rotenburo.

Kiryu · Multiple outdoor baths are consistently described, including a covered and uncovered section.

Naganohara · An outdoor bath (rotenburo) is present alongside the indoor bath at nearly every review.

Annaka · An outdoor bath exists, but under the current owner its area has been cut to under half its former size and depth reduced about 20% (kerosene heating cost cited); reviewers also report ants and horseflies and unclear rust/mold debris in the tub.

Minakami · A rock outdoor bath is available; bear-warning signs are posted right beside it given the mountain surroundings.

Showa · An outdoor bath is mentioned by many reviewers.

Higashiagatsuma · Both an indoor and an outdoor bath are available, facing a rocky mountain; one reviewer notes a swallow nest directly above the outdoor tub with droppings visible nearby, a hygiene concern with no posted warning.

Kawaba · An outdoor bath, usually described as noticeably milder/cooler than the indoor one, is present.

Minakami · An outdoor bath exists but is repeatedly described as extremely small, fitting only one or two people.

Katashina · A small half-outdoor bath is present and generally well liked, though one visitor reported it cold and poorly maintained on their visit.

Shinto · A small outdoor bath is available alongside the indoor tubs.

Tsumagoi · An outdoor bath exists but is closed in winter and only open in the warmer months, disappointing several off-season visitors.

Takasaki · One small outdoor bath alongside one indoor bath.

Higashiagatsuma · An outdoor bath exists but runs noticeably lukewarm (roughly body temperature to 38C), best enjoyed in warm weather.

Ota · An outdoor bath is present alongside the indoor baths.

Numata · The main baths include both an indoor tub and an outdoor (rotenburo) tub.

Numata · There are two outdoor baths (one warmer, one hotter).

Minakami · The facility consists of a single outdoor bath only, split into a few sections; there is no indoor bath.

Takasaki · Both indoor and outdoor baths are available, though the outdoor bath is not large.

Minakami · An outdoor bath overlooking the rice terraces is repeatedly described.

Minakami · Each private room includes outdoor-style baths (semi-outdoor and fully outdoor tubs) as part of its set, per many reviewers.

Shibukawa · An outdoor bath is confirmed.

Kawaba · An outdoor bath is widely confirmed.

Minakami · Four reviewers describe outdoor baths on site, though one 2025 reviewer said they saw nothing resembling an outdoor bath.

Katashina · There is one outdoor bath alongside the indoor bath, consistently praised for its setting.

Tomioka · A small outdoor bath overlooks the golf course and Mount Myogi.

Tsumagoi · A 2025 review describes both an outdoor and indoor bath, though an older (2020) review recalls indoor-only, suggesting the facility may have changed.

Midori · A single rock-style, partly-covered outdoor bath with a seating ledge for half-body soaking.

Tsumagoi · The inn's open-air bath (roughly hexagonal) comfortably fits two people, per one review.

Shibukawa · The affiliated hotel bath used by RV Park guests has an outdoor bath.

Minakami · One reviewer describes a jar-shaped outdoor bath.

Nakanojo · There is a spacious outdoor bath reached from the indoor bath, fed by the source spring.

Naganohara · A scenic outdoor bath is mentioned by multiple reviewers.

Minakami · This is a newer, spacious open-air bath with good scenery.

Minakami · This is an outdoor-only bath at the hotel.

Kusatsu · A large outdoor-only bath with a scenic view is here, separate from the actual spring source (which is fenced off and not enterable).

Tsumagoi · An outdoor bath is available with a view overlooking the spring source itself.

Takasaki · The women's bath area includes an outdoor (露天) tub in addition to the indoor one.

Minakami · The bath complex includes an outdoor bath alongside the indoor bath.

Nakanojo · Described as a garden-style outdoor bath fed by the hot spring source.