Ask any Japanese person to name the best hot spring town in Japan, and there’s a very good chance they’ll say the same word: Kusatsu. This small town in Gunma Prefecture has held the top spot in Japan’s hot spring rankings for decades — and the reasons are obvious the moment you arrive.
What Makes Kusatsu the #1 Onsen in Japan?
♨️ The Water Quality Is Extraordinary
Kusatsu’s hot spring water has a pH of around 2.1 — highly acidic and naturally antimicrobial. The water is so potent that there’s an old Japanese saying: “Kusatsu’s water cures all ailments.” The water volume is equally impressive: over 4,000 liters per minute flow from the earth naturally, making Kusatsu one of Japan’s highest-flow hot spring sources.
🌊 The Yubatake: One of Japan’s Most Famous Views
At the heart of Kusatsu sits the Yubatake (hot water field) — a large wooden framework where thousands of liters of steaming hot spring water flow every minute. At night, the Yubatake is illuminated, creating an otherworldly scene of steam and golden light. It’s one of the most photographed spots in all of Japan.
🏘️ The Best Onsen Town Atmosphere in Japan
Kusatsu’s town center is exactly what a Japanese onsen town should feel like. Guests wander in yukata robes between baths, steam rising around them. The streets are lined with souvenir shops, hot spring steamed buns, footbaths, and izakayas. It’s authentic in a way that purpose-built resort towns can never replicate.
What to Do in Kusatsu
- Soak at Nishi-no-Kawara Rotenburo — The famous open-air bath is massive and surrounded by forest
- Walk around the Yubatake at night — Illuminated and atmospheric; completely different from daytime
- Try the free footbaths — Multiple free footbaths around town; perfect for a break between soaks
- Eat onsen manju — Steamed sweet buns cooked using hot spring steam; every shop has its own variation
- Experience Jikan-yu — Kusatsu’s traditional bathing ritual: entering extremely hot water for a very short, intense soak
Getting There
From Tokyo (Shinjuku), direct highway buses take about 3 hours. Alternatively, take the Shinkansen to Karuizawa, then connect to Kusatsu by bus. Day trips are possible but one night minimum is strongly recommended.
Why Kusatsu Is Going Viral Internationally
International visitor numbers at Kusatsu have surged dramatically. “Kusatsu Onsen” videos flood TikTok and YouTube, with reaction videos from first-time visitors racking up millions of views. The combination of authentic atmosphere, photogenic scenery, and genuinely extraordinary water quality makes Kusatsu the perfect entry point into Japanese hot spring culture.
If you can only visit one onsen in Japan, make it Kusatsu.
