Sainokawara Rotenburo, Japan

What it is

Sainokawara Rotenburo is a very large outdoor bath set inside Kusatsu’s Sainokawara Park. It’s designed to feel closer to nature than an indoor bathhouse, with open sky, trees, and steam rising in cold weather. Despite the setting, it’s a managed facility with ticketing, changing areas, and a defined bathing space.

The experience

You come here for scale and the outdoor atmosphere rather than luxury. The bath is gender-separated and can hold a lot of people, which helps at peak times. In winter, the contrast between snow and hot water is the point, but it also makes access and footing more serious.

What to expect

It’s popular, and the walk through the park is part of the visit. If you want quiet, aim for off-peak times and avoid holidays.

Where it is

The bath sits within Sainokawara Park on the edge of Kusatsu Onsen town (Gunma Prefecture). It’s close enough to reach on foot from central Kusatsu, but far enough that weather matters.

Getting there

Many visitors arrive by bus to Kusatsu Onsen Bus Terminal, then walk through town toward the park. From the Yubatake area, it’s commonly described as roughly a 12-minute walk along onsen streets and park paths. In snow or rain, add time and wear grippy footwear.

What to bring

Bring a small towel and coin pouch for entry and lockers. Pack a warm layer for after your soak, because the walk back can feel cold. If you’re visiting in winter, traction can help on icy patches in the park.

Who it suits

This is for travelers who want a big, outdoor onsen without committing to an overnight stay. It’s also a good pick for groups because capacity is high and the town is built around walking between sights.

Families

Children are admitted with a child ticket, but manage expectations. The bath is outdoors, water can feel hot, and the walk back in winter is chilly. Bring a warm change of clothes and do not rush kids on wet stone surfaces.

Accessibility realities

This is not a barrier-free facility. Expect outdoor paths, wet surfaces, and transitions that can include steps and uneven ground. If you need step-free bathing, Kusatsu has other options, but you should confirm details rather than assuming.

Hot water and acidic springs

Kusatsu is known for strongly acidic hot spring water. That can be harsh on sensitive skin and small cuts. Rinse well after soaking and stop if you feel irritation. Avoid long soaks on your first round, and do not combine heavy drinking with a hot bath.

Outdoor hazards

In winter, snow and ice can make the approach slippery. Walk slowly, use railings where available, and keep a warm layer handy for the transition between changing and the bath. At night, visibility drops in the park, so stick to lit paths.

Etiquette basics

Wash first. Keep towels out of the bathwater. Do not take photos. Speak quietly and give people room at the rinse points. If you’re unsure where to rinse or where to place items, copy the local flow and ask staff rather than improvising.

How far is it from Yubatake?

It’s commonly reached on foot from central Kusatsu, with many visitors quoting about a 12-minute walk. In snow or crowds, allow extra time.

Is it open in winter?

Yes, it operates seasonally with different published hours. Check the official site close to your visit for the current schedule.

Are children allowed?

Yes, children are admitted with a child ticket. Plan around the outdoor setting and keep kids close on wet surfaces.

Do I need to bring toiletries?

Assume minimal amenities. Bring a small towel and basic wash items unless you’ve confirmed what’s provided.