Personal information for up to about 197,000 people who used the online reservation system for the Yoshida Route, the Yamanashi-side trail up Mount Fuji, may have leaked, the prefecture said on the fourth. The system is run by a contractor, and the breach struck a service used by that contractor's own vendor.
The prefecture said the reservation site operator Asoview, based in Tokyo, uses an email delivery system supplied by Tokyo-based Arara, and that the system was subject to unauthorized access. The data at risk covers membership details including email addresses, names and phone numbers, according to the prefecture.
Credit card numbers and login passwords were not among the exposed information, the prefecture said. The reservations in question were made for the 2025 and 2026 fiscal years.
Two vendors between the prefecture and the climbers
Yamanashi outsourced operation of the Yoshida Route booking site to Asoview, which in turn relied on Arara for email delivery. The prefecture announced the possible leak itself, putting the number of affected users at up to roughly 197,000.
The Yoshida Route is the most popular of the four trails on Mount Fuji and the one most used by first-time climbers. Yamanashi introduced online reservations for the route to ease congestion at the trailhead.