Checked against Gunma Prefecture’s own announcement pages and a local-government ordinance database on November 4, 2026. The exact dates of the annual spring climbing ban change every year, so if you’re heading to this specific mountain, confirm this season’s dates with the prefecture before you go.

If you’ve read about Nagano Prefecture’s climbing-plan requirement and assumed every Japanese mountain treats it as a polite ask, Tanigawa-dake in Gunma is the exception worth knowing about. It isn’t a city-wide rule or a blanket law covering all of Japan’s peaks — it applies to one specific danger zone on one specific mountain, under a prefectural ordinance that dates back decades because of the mountain’s climbing-accident history. Within that zone, filing a report isn’t a courtesy. It’s the law, and the prefecture can fine you for skipping it.

The rule only applies inside one defined “danger zone”

Gunma Prefecture’s Tanigawa-dake Disaster Prevention Ordinance (谷川岳遭難防止条例) defines a specific danger zone covering Ichinokura-dake and the rock-face terrain south of it — the technical climbing routes, not the mountain’s general hiking trails. If you’re on the standard tourist route up Tanigawa-dake via the ropeway, you’re not automatically in the zone this ordinance is built around. The exact boundary is shown on a map attached to the ordinance itself, so if there’s any doubt about your planned route, that’s the one thing worth checking before you go.

Inside the zone, filing 10 days ahead is mandatory — not optional

From March 1 through November 30, anyone entering the danger zone must file a climbing report with the Gunma Prefecture Tanigawa-dake Mountain Climbing Guidance Center, and the prefecture’s own guidance says to do it at least 10 days before you climb. Until April 2025, the only way to file was on paper — by mail, fax, or in person — to the Guidance Center or Numata Police Station. Since April 15, 2025, you can also file online through the YAMAP or Compass apps, which makes this realistically doable for a visiting climber without a Japanese address. Members of registered mountaineering clubs still file the equivalent paper form, but for everyone else, the app route is the practical option.

During winter — December 1 through the end of February — the rule softens: the ordinance only asks climbers to refrain from entering the danger zone, rather than requiring a filed report. That’s a recommendation, not a mandate, but it exists because winter conditions in this specific zone are considered dangerous enough that the prefecture would rather you simply didn’t go.

The governor can close the mountain outright — and does, almost every spring

Separately from the filing requirement, the ordinance gives Gunma’s governor the authority to prohibit climbing in all or part of the danger zone when conditions call for it — most commonly during the spring snowmelt period, when avalanche risk spikes. This isn’t a one-time historical rule; Gunma issues a dated closure notice most years. The most recent one on record at the time of writing ran 40 days, from March 16 through April 24, 2026. If your trip falls in that window in a future year, check the prefecture’s current announcement — the dates move depending on that year’s snow conditions.

Skipping either requirement is a criminal fine, not a warning

This is where Tanigawa-dake’s rule stands out from climbing-plan requirements elsewhere in Japan. Under Article 14 of the ordinance, climbing in the danger zone without filing the required report, or climbing during a governor-ordered prohibition, carries a fine of up to ¥30,000. That’s a criminal penalty under the ordinance, not an administrative slap on the wrist — and it’s a different mechanism from Nagano’s climbing-safety ordinance, which asks for a plan on its own designated trails but doesn’t carry the same criminal fine for skipping it.

Gunma isn’t alone in taking this approach. Toyama Prefecture runs a comparable ordinance for the climbing routes around Mt. Tsurugi (剣岳), where filing a false or missing climbing report carries a fine or minor fine of up to ¥50,000. Between the two, the pattern is the same: a small number of Japan’s most historically dangerous technical climbing zones are treated by law differently from the rest of the country’s mountains, where filing a plan is encouraged but not criminally enforced.

What this actually means for your trip

None of this applies if you’re doing the ropeway-and-observation-deck visit that most tourists do on Tanigawa-dake. It matters if your plan is to climb into the rock-face danger zone itself — in which case, file your report at least 10 days out through YAMAP or Compass, check whether your dates fall inside that year’s spring closure period, and keep the Guidance Center’s number on hand: 0278-72-3688.

How Travel AI Rescue helps

Travel AI Rescue keeps Japan’s emergency numbers — 110 for police, 119 for fire and ambulance — one tap away with the country code already attached, which matters most exactly where signal is weakest: partway up a mountain route. It can display Japanese-language cards describing your situation in plain terms, so a climber who doesn’t speak Japanese can still be understood immediately by whoever answers. And above all, it keeps your planned route and return time stored and readable on the device even with zero signal, which is exactly the kind of detail a filed climbing report is also meant to provide. It works differently from a staffed help desk or a travel insurance policy, and it’s with you around the clock — a bridge that gets you to the right emergency channel quickly and in the right words. (Filing the climbing report itself is done directly with Gunma Prefecture’s police or the Tanigawa-dake Mountain Climbing Guidance Center.)

Sources

• Gunma Prefecture, announcement on climbing report submission for the Tanigawa-dake danger zone, including the April 2025 move to online filing via YAMAP/Compass. https://www.pref.gunma.jp/site/houdou/697905.html (accessed 2026-11-04).
• Gunma Prefecture, announcement on the Tanigawa-dake danger zone general climbing plan submission and Guidance Center contact details. https://www.pref.gunma.jp/site/houdou/632817.html (accessed 2026-11-04).
• Research Institute for Local Government (地方自治研究機構), comparison of Japanese prefectural mountain-climbing ordinances, including Gunma Ordinance Article 14 and Toyama’s comparable ordinance. https://www.rilg.or.jp/htdocs/img/reiki/148_climbing.htm (accessed 2026-11-04).