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Showa Shinzan
🌲 Nature

Showa Shinzan

📍 Hokkaido, Sobetsu

A steaming red lava dome that pushed up out of a flat wheat field in the 1940s — Japan's youngest mountain, born in wartime and lovingly documented by the local postmaster who watched it grow.

Most mountains are unimaginably old. Showa Shinzan is not. Between 1943 and 1945, in the middle of a flat wheat field near Lake Toya, the ground bulged, cracked, and heaved upward into a steaming red dome of lava — and people stood there and watched it happen.

Why It’s Interesting

It is, in effect, Japan’s newest mountain, still warm and faintly smoking decades later, its rock baked a rusty red. The story is as good as the geology: with wartime authorities suppressing news of the eruption, the local postmaster, Masao Mimatsu, meticulously recorded the dome’s daily growth from his window — measurements scientists still use. He later bought the land to protect it. You can’t climb it (it’s protected and hot), but you can stand at its foot, watch it steam, and ride the nearby ropeway for the bigger picture.

Best Time to Visit

Year-round. The contrast of the red dome and its white steam against winter snow is especially dramatic.

Getting There

It shares a base area with the Usuzan ropeway near Lake Toya, reachable by bus from Toya Station or, more easily, by car on a Lake Toya loop.

🐿️ Cinnamon was here

Field report

In 1943, a Hokkaido wheat field started rising, and by 1945 it was a steaming red lava dome — Showa Shinzan, Japan's newest mountain, born in wartime secrecy while the local postmaster, Masao Mimatsu, measured its growth against a string because the government was too busy to document a whole new mountain.

His pencil-drawn growth charts (the 'Mimatsu Diagram') became internationally famous science, and his statue now faces the mountain he adopted. I sat at the statue's feet and looked where he looks: at a rust-red cone still steaming faintly, in a field that used to be flat.

The Usuzan ropeway next door gives you the dome, the lake, and the 2000 eruption scars in one ride. Mountains are usually older than everybody. Here, the grandmothers are older than the mountain. I love it here.

— Cinnamon 🐿️

📸 Cinnamon's camera roll

Snapshots from our very good boy on the road.

At the postmaster's statue's feet, looking where he looks: the rust-red cone that rose from a wheat field between 1943 and 1945, still steaming faintly.
Honoring the Mimatsu Diagram: he measured a newborn mountain's growth against a string because the government was too busy. Socks calls him the patron saint of documentation.
Showa Shinzan with Lake Toya
Photo via Wikimedia Commons
A steaming reddish-brown lava dome rising from flat ground with vents smoking
This whole mountain is younger than my grandpa. Wild.
Mon-chan and Cinnamon the squirrel before the steaming red lava-dome volcano
A mountain that grew out of a field. Cinnamon yelled 'YEAH!' at it. Fair enough. 🌋

Where it is

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