Mt. Fuji Sees Thousands of Illegal Climbers During Off-Season
Despite government closures, approximately 10,000 people illegally enter Mt. Fuji's trails annually during the off-season. GPS data analysis reveals that over 50% of these climbers are aged 50 or older, with the Fujinomiya route being the most frequently accessed. Local authorities are now seeking more effective measures to prevent accidents.
📋 Article Processing Timeline
- 📰 Published: June 1, 2026 at 18:34
- 🔍 Collected: June 1, 2026 at 18:49 (15 min after Published)
- 🤖 AI Analyzed: June 1, 2026 at 18:50 (1 min after Collected)
(CNA, Tokyo, June 1) According to estimates by Japanese media and a location data research firm, at least 10,000 people illegally enter Mt. Fuji's trails every year during the off-season. Although local governments have legally closed the trails, data shows that these measures have failed to deter climbers.
Japan's Yomiuri Shimbun reported that there are four climbing routes on Mt. Fuji: the Fujinomiya, Subashiri, and Gotemba routes on the Shizuoka side, and the Yoshida route on the Yamanashi side. These trails are only open from early July to September 10th each year, with the rest of the time designated as the off-season.
Due to the extremely high risk of mountain accidents during the off-season, the Shizuoka and Yamanashi prefectural governments, which manage the trails, have installed signs and barriers between the 5th and 6th stations (near the middle of the mountain) based on the Road Act, closing all routes to the summit. At the same time, local governments strongly urge the public not to enter the mountain from areas other than the designated trails.
"Gome" (station) is the unit used in Japan to measure the climb, divided from the 1st station at the base to the 10th station at the summit.
However, there are many people who enter during the off-season and encounter mountain accidents. According to data from the Shizuoka and Yamanashi prefectural police, between 2019 and 2025, a total of 79 people were involved in mountain accidents during the off-season, 19 of whom died.
Since the Japanese central government and the local autonomous organizations of the two prefectures had not previously grasped the actual situation of climbers during the off-season, the Yomiuri Shimbun, with the assistance of the location data research firm Location AI, used mobile phone location data to analyze foot traffic on the trails and estimated the number of climbers during the off-season from 2019 to 2025.
The results showed that, excluding 2020 due to the impact of COVID-19, an estimated 8,000 to 12,000 people climbed annually, with the highest numbers in June before the opening and September just after the closing. By route, the "Fujinomiya route," which is accessible by car from the 5th station and has the shortest distance to the summit, accounted for about 50%. By age group, people over 50 accounted for more than 50%.
This data does not include foreign tourists visiting Japan. Considering that foreigners account for 20% to 50% of climbers during the open season, and that cases of foreigners encountering mountain accidents during the off-season have occurred, the actual number is likely even higher than estimated.
An official from the Fujinomiya City government in Shizuoka Prefecture, which manages the Fujinomiya route, stated regarding the analysis results, "The number is higher than we imagined. In the future, we hope to work with the prefectural government to develop more effective response strategies."
This survey used mobile phone data from people living in Japan, including location information and user information, covering a scale of 93 million devices. These data came from applications that allowed external use by mobile phone users and were obtained by Location AI from data companies, with personal characteristics removed and anonymized.
During the analysis process, the research team set up data extraction areas between the 6th and 7th stations of each trail and estimated the daily number of climbers based on Japan's population size and structure.
To verify the reasonableness of the estimation method, the team also estimated the number of climbers during the open season in the same way. Regarding the open season, the Ministry of the Environment calculated the total number of climbers, and local autonomous organizations calculated the number of foreign climbers. After comparison, it was found that the value obtained by subtracting the "number of foreign climbers" from the "total number of climbers" was equivalent to the scale estimated by this analysis, thereby confirming its validity.
Japan's Yomiuri Shimbun reported that there are four climbing routes on Mt. Fuji: the Fujinomiya, Subashiri, and Gotemba routes on the Shizuoka side, and the Yoshida route on the Yamanashi side. These trails are only open from early July to September 10th each year, with the rest of the time designated as the off-season.
Due to the extremely high risk of mountain accidents during the off-season, the Shizuoka and Yamanashi prefectural governments, which manage the trails, have installed signs and barriers between the 5th and 6th stations (near the middle of the mountain) based on the Road Act, closing all routes to the summit. At the same time, local governments strongly urge the public not to enter the mountain from areas other than the designated trails.
"Gome" (station) is the unit used in Japan to measure the climb, divided from the 1st station at the base to the 10th station at the summit.
However, there are many people who enter during the off-season and encounter mountain accidents. According to data from the Shizuoka and Yamanashi prefectural police, between 2019 and 2025, a total of 79 people were involved in mountain accidents during the off-season, 19 of whom died.
Since the Japanese central government and the local autonomous organizations of the two prefectures had not previously grasped the actual situation of climbers during the off-season, the Yomiuri Shimbun, with the assistance of the location data research firm Location AI, used mobile phone location data to analyze foot traffic on the trails and estimated the number of climbers during the off-season from 2019 to 2025.
The results showed that, excluding 2020 due to the impact of COVID-19, an estimated 8,000 to 12,000 people climbed annually, with the highest numbers in June before the opening and September just after the closing. By route, the "Fujinomiya route," which is accessible by car from the 5th station and has the shortest distance to the summit, accounted for about 50%. By age group, people over 50 accounted for more than 50%.
This data does not include foreign tourists visiting Japan. Considering that foreigners account for 20% to 50% of climbers during the open season, and that cases of foreigners encountering mountain accidents during the off-season have occurred, the actual number is likely even higher than estimated.
An official from the Fujinomiya City government in Shizuoka Prefecture, which manages the Fujinomiya route, stated regarding the analysis results, "The number is higher than we imagined. In the future, we hope to work with the prefectural government to develop more effective response strategies."
This survey used mobile phone data from people living in Japan, including location information and user information, covering a scale of 93 million devices. These data came from applications that allowed external use by mobile phone users and were obtained by Location AI from data companies, with personal characteristics removed and anonymized.
During the analysis process, the research team set up data extraction areas between the 6th and 7th stations of each trail and estimated the daily number of climbers based on Japan's population size and structure.
To verify the reasonableness of the estimation method, the team also estimated the number of climbers during the open season in the same way. Regarding the open season, the Ministry of the Environment calculated the total number of climbers, and local autonomous organizations calculated the number of foreign climbers. After comparison, it was found that the value obtained by subtracting the "number of foreign climbers" from the "total number of climbers" was equivalent to the scale estimated by this analysis, thereby confirming its validity.
FAQ
When is the climbing season for Mt. Fuji?
It is generally open from early July to September 10th.