Mizunuma no Yu: A Hot Spring Right on the Watarase Railway Platform

Checked: September 27, 2026

Mizunuma no Yu is a day-use hot spring beside Mizunuma Station on the Watarase Keikoku Railway. The platform-to-bath walk is essentially zero, which makes it an unusually easy rural stop without a car. There is one catch to plan around: the railway operator currently lists the bath as closed on weekdays through October 2026, even though the facility page still shows its standard daily hours.

Check the operating calendar before looking at trains

For September 1–30 and October 1–31, 2026, railway notices list Mizunuma no Yu and Satoyama Honjin as open only on Saturdays, Sundays and public holidays. Weekday service is suspended during both periods.

The bath’s standard hours are 10 a.m.–9 p.m., last entry at 8 p.m. Its page also asks visitors to check the daily notice. No notice for November onward was posted when checked, so its schedule after October is unconfirmed.

When it is open, the standard adult admission is ¥1,350 on weekdays and ¥1,550 on weekends and holidays, including the ¥150 bathing tax. Children of elementary-school age and younger pay half price; children five and under enter free. Wednesdays are advertised as half-price “Mizunuma Day,” but this promotion cannot help on a weekday when the facility is closed. Busy days may also have entry limits for visitors without an in-house dining ticket.

The current “Yuasari Gozen” meal-and-bath bundles cost ¥2,800 or ¥3,400. Each includes admission, a towel set, a set meal and one drink. Choose a bundle for lunch and a soak; the basic ticket suits a short bath visit.

What the basic ticket covers

The public bath has indoor and outdoor pools, a sauna, and a cold plunge supplied with natural groundwater. That gives the standard admission a more complete bathing setup than a simple station-side bath. The cold plunge is specifically identified as groundwater; the facility does not publish the full water-handling details for each hot spring pool, so claims such as “all pools are free-flowing” would go beyond its published information.

The spring is listed as a cold mineral spring. There is a discrepancy in the facility’s own pages over the precise spring classification: the onsen page names a sodium/calcium chloride–bicarbonate cold spring, while its FAQ gives a fluoride–sodium–chloride classification. If the exact chemistry matters, use the current analysis certificate displayed on site rather than combining those labels into a new one.

The large open-air bath, Komorebian, needs separate attention. The facility announced in October 2025 that it was moving to fully reserved private use. The public onsen page still describes the bath but does not give current booking details or a price. A standard ticket should not be treated as access to Komorebian; contact the facility first if that bath is the reason for the trip.

Do not confuse the regular public-bath sauna with the separate Mori Sauna. The former is included in basic admission. Mori Sauna is a reserved, private product, with its TONTTU plan listed at ¥3,000 on weekdays and ¥3,500 on weekends and holidays; other private sauna plans cost more. These prices and reservations are separate from the public bath ticket.

How to make the railway stop work

Mizunuma Station is served by the Watarase Keikoku Railway, not a frequent urban line. The bath is attached to the station, but that only removes the last walk; it does not make a missed return train trivial. Check the timetable for your actual date, then choose your bathing window around the train home. Tourist trolley trains run seasonally and have their own reservation and ticket rules, so do not assume a regular rail pass also covers the trolley.

By car, the facility lists free parking beside Mizunuma Station and additional spaces near Kurohone Sports Park. The railway is the more distinctive way to arrive, though: the bath works particularly well as one stop on a day exploring the Watarase valley, rather than as a quick Tokyo out-and-back for a single soak. For another railway-side bath in the same broad mountain corridor, see the Doai Yufuki-no-Yu day-bath guide. The Gunma onsen overview compares destinations with very different transport demands.

Sauna, tattoos and what to confirm

The bath FAQ says guests may use the public bath if tattoos are fully covered; the facility sells cover seals for ¥600 each. The sauna-related wording on the facility’s pages is not fully consistent, so do not assume that a seal automatically settles sauna access. If the seal’s size or placement might leave part of a tattoo exposed, ask at reception before paying.

The railway is the reason to make this a stop on a Watarase Valley day, not a quick out-and-back from central Tokyo. The bath opens at 10 a.m., so arriving on one of the earliest trains does not mean you can bathe straight away. Reverse-plan from the return train; the station-to-bath connection is effortless, but the rural rail timetable still sets the length of your visit.

Before leaving, check three things on the same day: whether the bath is open, whether your train gives you enough time for a comfortable visit, and whether any special use of Komorebian requires an advance booking. Those details matter more here than adding another stop to the itinerary.

Sources

- [Mizunuma Village: onsen facilities, rates and standard hours](https://mizunuma-village.jp/onsen/) - [Mizunuma Village: FAQ on operating hours, station access, parking and tattoos](https://mizunuma-village.jp/faq/) - [Watarase Keikoku Railway: October 2026 operating-day notice](https://www.watetsu.com/news/news_det.php?E=2003) - [Watarase Keikoku Railway: September 2026 operating-day notice](https://www.watetsu.com/news/news_det.php?E=1991) - [Mizunuma Village: notice moving the large open-air bath to private, reservation-only use](https://mizunuma-village.jp/news/%E3%80%90%E6%B0%B4%E6%B2%BC%E3%81%AE%E6%B9%AF%E3%80%80%E5%A4%A7%E9%9C%B2%E5%A4%A9%E9%A2%A8%E5%91%82%E3%81%AE%E8%B2%B8%E5%88%87%E5%B0%82%E7%94%A8%E5%8C%96%E3%81%AB%E3%81%A4%E3%81%84%E3%81%A6%E3%80%91/) - [Watarase Keikoku Railway: timetable, fares and ticket information](https://www.watetsu.com/)

Tags: Mizunuma no Yu, Mizunuma Station, Watarase Keikoku Railway, Gunma onsen, Kiryu day trip