Sainokawara Park/Open-Air Bath
The surrounding area is designated as a special zone within Joshin'etsukogen National Park, and a large open-air bath has been constructed at its innermost point. True to its status as one of Japan's three most famous hot springs—and boasting the country's highest volume of naturally gushing hot spring water—Kusatsu Onsen sees 1,400 liters of water welling up every minute from various points across the wide riverbed. This water flows out to form a "river of hot water," creating a magical landscape of cascades and pools. The park is illuminated from sunset until midnight, allowing visitors to enjoy a romantic evening stroll after their bath.
View scenic routes that include this spot
Rejuvenate through Nature and Traditional Culture on a Tokyo–Gunma Retreat
More Information about Sainokawara Park/Open-Air Bath
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Street address
- 521-3 Kusatsu, Kusatsu, Agatsuma District
About GUNMA
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Access
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- About 15 minutes on foot from Kusatsu Onsen Bus Terminal
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Opening Hours
- 【Open-Air Bath】7:00 a.m. to 8:00 p.m. (April to November); 9:00 a.m. to 8:00 p.m. (December to March). Last admission for both is at 7:30 PM.
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Closed
- Open daily, though closed occasionally for maintenance.
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Best season
- All year
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Point
- Located to the west of Kusatsu Onsen, hot spring water gushes from the ground all around, sending up clouds of steam and flowing into the Yu-gawa River — a unique, acidic thermal river flowing directly from Mt. Kusatsu-Shirane powerful volcanic sources.
Due to its appearance, the area is feared and known as "Oni no Sensui" (Demon's Spring); local legend holds that one must not raise one's voice here, lest a demon appear.
At night, the area is illuminated, offering a magical, otherworldly atmosphere that differs greatly from the daytime view.
update: Oct.28.2026
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