This is one of the most accessible yet exciting hikes near Tokyo, perfect for beginners looking for a half-day mountain adventure. Just don't go on or after a rainy day. Within the first 30 minutes, you'll find yourself trekking alongside a rocky stream, climbing ladders, and walking through lush forest. The loop trail takes about 4 to 5 hours and offers great views of the Okutama and Chichibu mountain ranges from the summit.

Trailhead:
Sawara-bi no Yu (さわらびの湯) Bus Stop

Access:
By Car:
Free parking available near Sawara-bi no Yu Onsen (Note: fills up fast on weekends)

By Public Transport:
Take the Seibu Ikebukuro Line from Ikebukuro Station to Hanno Station (~50 mins).
From Hanno, take a bus bound for 名栗 (Naguri) and get off at Sawara-bi no Yu (~40 mins).
The trailhead is a 10-minute walk from the bus stop.

Hike Details:

• Distance: Approx. 9–10 km (loop)

• Duration: 4 to 5 hours

• Incline: About 600 meters

General Information & Summary:
Bonooreyama (969m) is a popular peak in the Saitama-Tokyo border region, known for its dynamic stream-side trail and rewarding summit views. Starting from the Sawara-bi no Yu area, the Shirayasusawa course takes you up a narrow, rocky river gorge with wooden ladders, clear pools, and cool forest air. It’s a trail that feels far more adventurous than its proximity to Tokyo would suggest.

After reaching the summit, you'll be treated to a wide-open view of the Okutama Mountains, and on clear days, you may even spot Tokyo skyscrapers in the distance. The descent follows a wider forest road, making for a relaxed return. For those seeking more challenge, extended routes connect to nearby mountains like 川苔山 (Kawanoriyama).