Onsen Guide · Gunma, Japan
This guide to Kusatsu Onsen covers whether it is worth the trip from Tokyo, how to get there, what the public baths cost and which ryokan actually bathe in the town's own source water. Kusatsu pushes out at least 32,300 litres of hot water a minute, the largest natural outflow of any onsen town in Japan.
Yes, and the numbers explain why. The town pushes out at least 32,300 litres of hot water a minute, the largest natural outflow in Japan, and the water at the Yubatake source is pH 2.1, among the most acidic in the country, at around 131°F / 55°C before cooling. Thirteen public baths are open to visitors, the Yubatake itself sits in the middle of town, and Kusatsu stands about 1,200 m above sea level in Gunma Prefecture, northwest of Tokyo, so August highs sit around 77°F / 25°C.
It suits travellers who want a proper onsen town rather than a resort strip: walkable streets, water everywhere, a public bath a few minutes from your door. It also suits anyone planning a winter trip, since the ski resort, the yumomi shows and the steam off the Yubatake all work in the cold.
The Yubatake is the hot water field at the centre of Kusatsu, and its source alone delivers 4,000 litres a minute at around 131°F / 55°C. The water runs through a set of long wooden chutes, cooling as it flows while keeping its minerals. It is one of six sources in town.
Beside the field is Netsunoyu, where workers cool the water by stirring it with long wooden planks in time to a folk song. The yumomi show runs six times a day and costs $4 (¥700) for adults.
Day visitors can bathe at several baths around town, and the table below gives prices and times for the main ones. Dollar figures use 159 yen to the dollar.
| Bath | Adult entry | Hours | Worth knowing |
|---|---|---|---|
| Otakinoyu | $8 (¥1,200), children 3-12 $4 (¥600), towel set $2 (¥250) | 9:00-21:00, last entry 20:00 | Awase-yu is a series of baths taken in turn from 100°F / 38°C to 115°F / 46°C, cooled naturally not diluted. Cloudy mineral-rich water on the 2nd and 4th Saturday each month. |
| Sainokawara open-air bath | $5 (¥800), children 3-12 $3 (¥400) | 7:00-20:00 to 30 November, 9:00-20:00 from 1 December, last entry 19:30 | 500 square metres holding up to 100 people. Separate for men and women, mixed on Friday evenings. A 12-minute walk from central Kusatsu. |
| Netsunoyu yumomi show | $4 (¥700), elementary child $2 (¥350) | Six shows a day: 9:30, 10:00, 10:30, 15:30, 16:00, 16:30 | A show, not a bath. Workers cool the water with long wooden planks to a folk song. Winter schedule from 1 December to end of February: 10:00, 10:30, 11:00, 15:30, 16:00, 16:30. |
| Otakinoyu private Shakunage bath | $13 (¥2,000) per hour rental | Within Otakinoyu hours | Rentable by couples and families, barrier-free. |
Allow about 3 hours by limited express train plus bus, or about 4 hours by highway bus from central Tokyo. Kusatsu has no train station, so every rail route ends with a bus ride. The table shows the main options.
| Route | Legs | Time |
|---|---|---|
| Limited express from Ueno | JR limited express Kusatsu-Shima from Ueno to Naganohara-Kusatsuguchi, then JR bus to Kusatsu | About 2 h 33 min on the train, 25 min bus |
| Shinkansen via Karuizawa | Hokuriku Shinkansen Tokyo to Karuizawa, then Kusatsu Kotsu or Seibu Kanko bus | About 1 h 10 min on the train, 1 h 18 to 1 h 55 min bus |
| Highway bus | Joshu Yumeguri-go from Tokyo Station or Busta Shinjuku, plus routes from Shibuya, Ikebukuro, Kichijoji, Yokohama and Omiya | About 4 hours |
| Local trains via Takasaki | Ueno to Takasaki, Agatsuma Line local to Naganohara-Kusatsuguchi, then bus | About 1 h 45 min plus 1 h 30 min plus 25 min bus |
| Car | Drive from Tokyo | Around 3 hours |
Kusatsu has 6 hot spring sources, and the ryokan that advertise the source water usually name which one they draw from. Hotel Ichii, the closest ryokan to the Yubatake and over 300 years old, uses 2 of the town's 6 sources and runs both kake-nagashi, meaning free-flowing with no recirculation. The slightly cloudy white water of the Shirahata source fills the large bath, and the clear water of the Bandai source, piped from Mount Shirane, fills the open-air bath. Its 23 main-building rooms look over the Yubatake.
Naraya sits beside the Yubatake and was founded in 1877. It bathes in the Shirahata source, said to be the oldest in Kusatsu, piped to the inn down the natural slope of the land.
When a listing says hot spring, ask two things: which source the water comes from, and whether it is kake-nagashi or recirculated. If a ryokan names neither, treat the hot spring claim as unconfirmed. The guide to what counts as a hot springs hotel explains the four things the phrase can mean, and this Kusatsu ryokan search shows every option in town.
Yes. Otakinoyu rents its private Shakunage baths at $13 (¥2,000) an hour for couples and families, and the rooms are barrier-free.
For a bath inside your own room, start with the guide to ryokan with a private onsen. Hakone onsen ryokan are the stronger bet for in-room bathing: five of them put a private onsen in every room.
Kusatsu is open all year, and winter is its strongest season: the ski resort usually runs from the end of December to the end of March, overnight lows reach around 14°F / -10°C, and the yumomi shows move to their winter schedule of 10:00, 10:30, 11:00, 15:30, 16:00 and 16:30. Summer highs sit around 77°F / 25°C, a relief compared with Tokyo.
With a car and the mountain road open, add a side trip to Manza Onsen, a village 1,800 m up Mount Kusatsu-Shirane that Japan Guide describes as having Japan's most sulfuric waters.
Hot Spring Stays has no Kusatsu hotel page yet, so the ryokan compared in detail come from the three onsen towns it does cover. The table sets Kusatsu against them.
| Onsen town | From Tokyo | Why go | Our guide |
|---|---|---|---|
| Kusatsu | About 3 hours | Largest natural outflow in Japan, pH 2.1 acid water, 13 public baths | No page yet |
| Hakone | See guide | Closest of the three to Tokyo, five ryokan with a private onsen in every room | Hakone onsen ryokan |
| Kinosaki | See guide | Free public-bath pass handed to you with your ryokan stay | Kinosaki onsen ryokan |
| Beppu | See guide | Eight districts of different water, hot sand and mud bathing | Beppu onsen hotels |
Hot Spring Stays has no Kusatsu location page yet, so these are the onsen ryokan with source water on site from the three Japanese towns this guide to hot springs hotels compares: Hakone, Kinosaki and Beppu.
Hakone Suishoen offers an in-room rotenburo available around the clock.
Yoshiike Ryokan draws on six proprietary sources running 109–176°F / 43–80°C.
Tonosawa Ichinoyu Honkan has an alkaline simple hot spring at the lowest starting price of the Hakone three.
Nishimuraya Honkan uses the town source at 177.8°F at the wellhead, with the yumepa pass covering the public baths.
Sanso Kannawaen has 100% source-flowing baths in the rooms.
AMANE RESORT SEIKAI puts a room open-air tub with source water in your own space.
Source: Kusatsu Onsen Tourism Association, Otakinoyu, Sainokawara, Netsunoyu yumomi, Access by train, Hotel Ichii, Naraya, Visit Gunma.
Kanagawa
9 with water on site
Two of twelve Hakone ryokan publish a tattoo policy at all, and five put a private onsen in every room, which makes the question moot.
Read the guide →
Hyogo
7 with water on site
Your ryokan hands you a free pass to the town's public baths, so its own tub is the least important thing about it.
Read the guide →
Oita
9 with water on site
The famous cobalt and blood-red pools are for looking at: what you actually get into here is hot sand, grey mud, and eight districts of different water.
Read the guide →