Arcadia disaster information system breach causes widespread data leaks in Japan

data breach cyberattack disaster information system personal information leak municipal services

A major cybersecurity incident involving the IT company Arcadia has led to widespread potential personal data leaks across numerous Japanese municipalities. The breach targeted the SpeeCAN RAIDEN disaster information distribution system, which is used by approximately 800 local governments nationwide to disseminate emergency alerts, weather warnings, and disaster information.

Arcadia reported that the unauthorized access could affect up to 3,136,000 email addresses and 105,000 phone numbers. Affected regions include Kyoto, Aomori, Akita, and Wakayama, among others. Specific impacts vary by municipality: Matsusaka City reported a potential leak of 8,363 items, including approximately 1,043 citizens' facial photographs. Wakayama City noted a potential leak of over 23,000 pieces of information, including resident emails and staff details. In Aomori, approximately 7,900 pieces of information were potentially compromised.

In addition to the Arcadia breach, Kushiro City reported a separate incident where a contractor's server was accessed, potentially exposing the information of 31,000 students and faculty members. Local governments have responded by suspending affected services, such as disaster email alerts and emergency reporting systems like NET119, and are urging citizens to remain vigilant against suspicious emails and phone calls.

Entities

Akita City · Arcadia · Arcadia Co., Ltd. · Kazuno City · Matsusaka City · Medley · Oita City · Okayama City · Saga City · SpeeCAN RAIDEN · Wakayama City

Claims

What the coverage asserts, and how many sources carry each claim.

[○ 1 SOURCE] Kyoto City suspended its disaster information distribution service due to potential leaks of community leader and staff data. www.city.kyoto.lg.jp
[○ 1 SOURCE] Ayabe City in Kyoto Prefecture reported a potential leak of 185 names and email addresses from an SOS mail system.
[○ 1 SOURCE] Wakayama City announced a potential leak of over 23,000 pieces of personal information. wakayamashimpo.co.jp
[○ 1 SOURCE] Matsusaka City reported a potential leak of 8,363 items, including approximately 1,043 citizens' facial photographs. yomotto.jp
[○ 1 SOURCE] Akita, Yokote, and Yurihonjo cities in Akita Prefecture reported potential leaks of resident information.
[● 2 SOURCES] The potential leak involves up to 3,136,000 email addresses and 105,000 phone numbers. yomotto.jp · piyolog.hatenadiary.jp
[● 9 SOURCES] Arcadia confirmed unauthorized access to its SpeeCAN RAIDEN disaster information distribution system on October 11, 2026. www.aba-net.com · fm791.net · yomotto.jp · piyolog.hatenadiary.jp · wakayamashimpo.co.jp · +1 more
[○ 1 SOURCE] In Oita Prefecture, five cities reported potential leaks, including 32,000 items in Oita City.
[○ 1 SOURCE] Aomori City announced that approximately 7,900 pieces of information may have been leaked. www.aba-net.com
[○ 1 SOURCE] Kushiro City announced that information for approximately 31,000 students and staff may have been leaked. www.nishinippon.co.jp
[○ 1 SOURCE] A total of 65 items were potentially leaked from the NET119 emergency reporting system. www.sakigake.jp