Sainokawara Park Kusatsu Travel Guide

Basic Information

The Sainokawara Open-Air Bath is open every day of the year. From April to November, the bath opens at 09:00 and closes at 20:00 (last entry 19:30). From December to March, hours shift slightly — check the official site or call ahead at 0279-88-6167 to confirm current winter closing times before you travel. The park surrounding the bath is freely accessible at all hours.

Admission is 600 yen for adults and 300 yen for children. Cash only — there are no card payment facilities at the entrance. Towel rental is available at the counter, or you can bring your own small towel. No large towels, shampoo, or soap are permitted inside the bathing area. There are vending machines near the entrance for drinks.

A mixed-bathing session runs every Friday from 17:30. During this window, the men's bath is used for mixed-gender bathing (this is the rotenburo section). The facility is gender-separated at all other times. The official website in English is at onsen-kusatsu.com/sainokawara/en and lists any seasonal schedule changes.

Tattoo Policy at Sainokawara

Sainokawara Open-Air Bath is fully tattoo-friendly. Guests with tattoos of any size enter the communal pool without restriction and without needing to cover them. This has been consistently confirmed by visitors bathing here, including guests with large visible tattoos, through 2026. No waterproof patches or sleeve coverings are requested by staff.

This policy applies during both gender-separated hours and the Friday mixed-bathing session. It is one of relatively few large public outdoor baths in Japan where the tattoo policy is this straightforward, which is part of why it draws significant international visitor interest. If you are uncertain about policies at other onsen in Kusatsu, always verify directly with the facility before visiting.

Other onsen in the Kusatsu area, such as Otaki no Yu, have their own separate policies. Sainokawara's open stance makes it the clearest recommendation for tattooed visitors looking for an outdoor bath experience in the Kanto region. The Kusatsu Onsen Public Baths Travel Guide guide covers the other main options in town and their access rules.

Bathing Experience and Onsen Etiquette

There are no shower stations inside Sainokawara. Unlike most indoor onsen, you do not wash before entering — you soak directly in the spring water. This is normal for this type of outdoor rotenburo. Bring a small towel: fold it and place it on the edge of the pool or on your head while soaking. It must not enter the water.

Bathing is done completely without clothing. Swimsuits are not permitted. The bath is gender-separated with a solid dividing wall, and each side offers independent access to the pool. The Friday mixed-bathing session from 17:30 uses the men's side. The water is strongly acidic (Kusatsu's pH typically runs around 2) with a sulfurous, slightly sharp taste in the steam. Most visitors adapt within a few minutes.

Temperature management is practical here: the Bandai source delivers very hot water near the inlet pipe. If you find the heat intense, move toward the far edges where the water has had more time to cool against the stone. In winter, the contrast between cold air and hot water is significant — the steam visibility is at its highest and the experience is particularly striking. Avoid staying in for extended periods on your first visit; 15–20 minutes is a reasonable starting point.

There are no lockers inside the main bath area. Leave valuables in your accommodation or in a coin locker at the bus terminal before entering the park. After bathing, the exit leads back through the park gates — the 10-minute walk back to Yubatake is a natural cool-down.

The Free Park Walk and Foot Baths

The park surrounding the bath costs nothing to enter. The trail from the park gate to the bath entrance passes through roughly 500 meters of geothermal landscape: hot streams cut through the valley floor, the rocks are stained rust and yellow from mineral deposits, and small geothermal pools bubble beside the path. This alone is worth the walk even if you do not plan to pay for the bath.

Several spots along the park streams are shallow enough to use as informal foot baths (足湯, ashiyu). The water temperature in the streams varies — some sections are too hot, others cool enough to sit beside and dip feet in briefly. There are no designated signposted ashiyu stations inside the park itself, so be cautious: test the temperature with your hand before putting feet in any stream. On some days park management restricts foot bathing in specific areas, so follow any posted notices.

The park also features jizo statues adorned with red bibs along the paths — these small guardian figures are a quiet cultural detail worth pausing at. A small shrine sits further up the hillside, accessible by a short detour from the main trail. The park is free and open at all hours, making it a pleasant place to walk in the morning before the bath opens or in the evening after a soak. There are no cafes or food stalls inside the park, so bring drinks from the town center before entering.

Why Bathe Here: What Makes Sainokawara Different

Kusatsu onsen water is among Japan's most acidic and mineral-dense. The Bandai source that feeds Sainokawara has a pH of roughly 2 and a high sulfur and chloride content. Traditional accounts credit Kusatsu water with antibacterial properties, and the area has been a therapeutic bathing destination for centuries — the town's onsen history is documented from at least the Edo period. The open-air setting at Sainokawara means the therapeutic water is combined with mountain air and seasonal scenery.

Scale is the other distinguishing factor. Most onsen in Japan — even outdoor ones — are relatively compact. Sainokawara's 500-square-meter pool is large enough that you genuinely never feel crowded. You can find a stone ledge in a far corner, let the steam close around you, and lose track of time. This spaciousness is unusual and is consistently what visitors report as the standout quality of the experience.

The tattoo-friendly policy expands who can use it. A significant share of international visitors to Japan carry tattoos and are excluded from many traditional onsen facilities. Sainokawara removes that barrier without compromise on quality — the water, the setting, and the scale are all at the top end of what Kusatsu offers publicly.

Getting There and Planning Your Visit

From Tokyo, take the JR Agatsuma Line or a direct highway bus from Shinjuku Bus Terminal to Kusatsu Onsen Bus Terminal. Direct highway buses from Tokyo take around 2 hours 40 minutes and run several times daily — this is the most convenient option for a day trip. From the bus terminal, Sainokawara Park is a 10–12 minute walk west, passing through the Yubatake area. Signage along the main street points toward the park.

For timing, arriving at or shortly after opening (09:00 April–November) gives the quietest experience. Weekday mornings are significantly less busy than weekend afternoons. The Friday evening mixed-bathing session from 17:30 attracts a specific crowd and can be busier than typical weekday evenings. If you want solitude, a weekday morning or late afternoon visit is the best bet.

Allow at least two hours for a full visit: 10 minutes walking from Yubatake through the park, a 45–60 minute soak, time to dress and cool down, and the walk back. Combine with a stop at Yubatake on the return — the hot water field at the center of town is free to view and takes about 20 minutes to walk around. You can also check the Kusatsu Onsen From Tokyo Travel Guide guide for full itinerary options including the Yumomi show at Netsunoyu.