Mt. Tomisan

Mt. Tomisan (富山, 349.5 m) is a mountain in Minamibōsō, Chiba Prefecture, and one of the 100 Famous Mountains of Kantō. It is a twin-peaked mountain with the North Peak (Konpira Peak, 349.5 m) and the South Peak (Kannon Peak, 342 m); the North Peak holds the “Eleven Provinces Lookout,” a viewpoint known since the Edo period that takes in the Bōsō hills and the sea. The mountain is famous as a setting of Kyokutei Bakin’s epic “Nansō Satomi Hakkenden” (The Eight Dog Chronicles), and the Fusehime Cave and the Dog’s Grave remain on its slopes.
The nearest station is Iwai on the JR Uchibō Line; this popular low mountain of Bōsō can be climbed on foot straight from the station.

Mt. Tomisan is one of the 100 Famous Mountains of Kantō. Everything is within walking distance of Iwai Station: head from the station to the Fukuman-ji trailhead and climb to the summit in about 2 hours up and 1 hour 30 minutes down. A Konpira shrine sits in the saddle between the North and South peaks, and the North Peak lookout is the high point.

*Timetable last checked: unverified

1. [Outbound] Iwai Station → Fukuman-ji → Tomisan (North & South peaks)
2. [Return] Tomisan → Fusehime Cave & Dog’s Grave → Iwai Station
3. Recommended plans & area info

1. [Outbound] Iwai Station → Fukuman-ji → Tomisan (North & South peaks)

Get off at Iwai Station on the JR Uchibō Line and walk east through farmland to the Fukuman-ji trailhead (about 30 minutes from the station). From here the real trail begins; switchbacks through planted forest and a final flight of steps lead to the saddle between the two peaks. A few minutes from the saddle brings you to the North Peak (Konpira Peak, the high point) and its “Eleven Provinces Lookout”. It is about 2 hours from Iwai Station to the summit. The South Peak (Kannon Peak) has a Kannon hall and also offers open views.

Reference: Minamibōsō Iitoko-dori — Tomisan & Iyogatake hiking

2. [Return] Tomisan → Fusehime Cave & Dog’s Grave → Iwai Station

For the descent you can retrace your steps, or take the popular loop down the Okusawa forest road past the Fusehime Cave and the Dog’s Grave. These mark the cave where Princess Fuse and her dog Yatsufusa are said to have lived in “Nansō Satomi Hakkenden,” and Yatsufusa’s grave; from there return toward Tomi Junior High School and Iwai Station (about 1 hour 30 minutes down). The forest-road section is long, so allow plenty of time. There are no shops on the mountain, so prepare food and water near Iwai Station.

Reference: Mt. Tomisan (Chiba) — Wikipedia

3. Recommended plans & area info

Day-trip loop: Iwai Station → Fukuman-ji → Tomisan (North & South peaks) → Fusehime Cave & Dog’s Grave → Iwai Station (about 4 hours). Rewarding for a low mountain, with literary sites from the Hakkenden along the way.
Traverse: A ridge route also links neighboring Mt. Iyogatake (the “Matterhorn of Bōsō”), so strong walkers can enjoy both peaks in a day.

Photo by Σ64 / CC BY 3.0