Mt. Kusatsu-Shirane — Emerald Crater Lake and Alpine Flowers on an Active Volcano
Hiking guide for Mt. Kusatsu-Shirane (2,171m), one of Japan's 100 Famous Mountains. Features the Moto-Shirane exploration trail with koma-kusa alpine flowers. Active volcano — always check current access restrictions before visiting.
Nearest Station
🚉 Naganohara-Kusatsuguchi Station (JR Agatsuma Line)
JR Agatsuma Line (about 3 hours from Tokyo) + JR Bus about 30 min
Duration
⏱ About 3-4 hours (loop)
Distance
📏 About 6km
Elevation
⛰ 2171m
Best Season
Summer, Autumn
Family Friendly
✅ Yes
Registration
✅ Not Required
Gear Level
🎒 Standard Gear
Trail Overview
Mt. Kusatsu-Shirane (草津白根山) is an active volcanic group north of Kusatsu Onsen in Gunma Prefecture. Its highest peak, Moto-Shirane (本白根山, 2,171m), is designated as one of Japan’s 100 Famous Mountains.
⚠️ Important: Access Restrictions
Mt. Kusatsu-Shirane is an active volcano. Access restrictions change based on the volcanic alert level.
- January 2018: Moto-Shirane erupted (alert level raised to 3)
- Yugama (Shirane-san) and Moto-Shirane have separate alert levels
- Always check before visiting:
- Japan Meteorological Agency volcanic activity updates
- Gunma Prefecture and Kusatsu Town latest restriction information
The routes described below are accessible only when restrictions are lifted.
Recommended Route: Moto-Shirane Exploration Trail (Loop)
A loop course from the Shirane-san Resthouse visiting the Moto-Shirane viewpoint area.
Course Time
| Section | Duration |
|---|---|
| Shirane-san Resthouse → Moto-Shirane Trail Entrance | About 50 min |
| Trail Entrance → Moto-Shirane Viewpoint | About 20 min |
| Viewpoint → Kagami-ike (Mirror Pond) | About 30 min |
| Kagami-ike → Yumi-ike & Resthouse | About 40 min |
| Total (loop) | About 3 hours |
Tip: From the Moto-Shirane viewpoint, enjoy a panoramic view of Mt. Asama, Mt. Azumaya, and the Northern Alps on clear days.
Koma-kusa: Moto-Shirane is famous for its koma-kusa (Dicentra peregrina) colonies — delicate pink alpine flowers blooming on volcanic gravel. Peak season is early to mid-July. Stay behind the protective fences.
Access Information
- Nearest Station: JR Agatsuma Line, Naganohara-Kusatsuguchi Station
- From Tokyo: JR Limited Express “Kusatsu” to Naganohara-Kusatsuguchi (about 2.5 hours) → JR Bus to Kusatsu Onsen (about 30 min)
- From Kusatsu Onsen: Bus from Kusatsu Onsen Bus Terminal to Shirane-san Resthouse, about 30 min via Shiga-Kusatsu Kogen Route
- By Car: Kanetsu Expressway Shibukawa-Ikaho IC → National Routes 353/292, about 2 hours. Paid parking at Shirane-san Resthouse
- Winter Closure: National Route 292 (Shiga-Kusatsu Kogen Route) is closed November through April
Convenience Stores, Shops & Restrooms
Convenience Stores (within 5 min of trailhead)
- Lawson Kusatsu Onsen: Near the Kusatsu Onsen Bus Terminal — stock up before heading up
- No convenience stores near the Shirane-san Resthouse. Prepare supplies in Kusatsu Onsen
Shops & Teahouses
- Shirane-san Resthouse: Light meals, beverages, and souvenirs available. Starting point for the trail
- Near Yumi-ike: Small shops near the resthouse area
Restrooms
- Shirane-san Resthouse: Indoor restrooms available
- Near Yumi-ike: Public restrooms available
- No restrooms along the exploration trail itself
Highlights
Yugama Crater Lake
- A crater lake atop Mt. Shirane with a mesmerizing emerald-green surface, about 300m in diameter
- Access may be restricted depending on volcanic alert level
- When accessible, about a 20-minute walk from the resthouse
Koma-kusa Alpine Flower Colonies
- One of Japan’s largest koma-kusa colonies on Moto-Shirane’s volcanic gravel slopes
- Peak bloom in early to mid-July. Do not enter fenced areas
Yumi-ike (Bow Pond)
- A small crater lake near the resthouse with beautiful sky reflections
- A 15-minute walking path circles the pond
Kusatsu Onsen
- After hiking, enjoy one of Japan’s most famous hot spring towns
- Multiple public baths centered around the iconic Yubatake (hot water field)
- About 30 minutes from the resthouse by bus
Gear Checklist
- ✅ Hiking shoes (trails are maintained but include volcanic gravel sections)
- ✅ Rain jacket and pants (weather changes quickly at summit level)
- ✅ Lunch and trail snacks
- ✅ Water (minimum 1L)
- ✅ Warm layer (above 2,000m — strong winds significantly lower felt temperature)
- ✅ Sunscreen and hat (exposed gravel areas with no shade)
- ⬜ Face mask (for those sensitive to volcanic gases)
Important Notes
- Check access restrictions first: Restrictions change with volcanic alert levels. Always verify on the day of your visit
- Volcanic gases: Hydrogen sulfide and other volcanic gases are present in some areas. If you detect a strong odor, move away immediately
- Winter closure: Route 292 is closed November through April — no access in winter
- Afternoon thunderstorms: At 2,000m+, afternoon thunderstorms are common in summer. Start early