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Government

Minamiboso City

Minamiboso City (Minamiboso, Chiba; Municipality) appears in 2 related cybersecurity incidents. The latest was disclosed on 2026-10-13.

Profile

Industry/type: Municipality
Location: Chiba, Minamiboso
Website: https://www.city.minamiboso.chiba.jp/

Public figures

Residents33,3912026-01-01
MIC: 住民基本台帳に基づく人口、人口動態及び世帯数（令和8年1月1日現在）

Metric	Value		As of	Source
Residents	33,391		2026-01-01	MIC: 住民基本台帳に基づく人口、人口動態及び世帯数（令和8年1月1日現在）

Incident history

Disclosed 2026-10-13Updated 2026-10-26 12:51Aichi, Chiba, Fukuoka, Hiroshima, Hyogo, Kagoshima, Kanagawa, Oita, Okayama, Osaka, Saitama, Tochigi[Investigating][Severity: Critical][Through a supplier][Major]
Arcadia: unauthorized access to the SpeeCAN RAIDEN alert service
[Web app exploit][Data leak][Service outage]Leaked 3.1MOrganizations 28
Disclosed 2020-03-12Updated 2020-03-17 08:00Chiba[Resolved][Severity: Moderate][Through a supplier][Moderate]
Minamiboso City Tourism Association: prize emails for a Minamiboso city coupon draw carried a list of 1,577 entrants
[Misdelivery][Data leak]Leaked 1.6KOrganizations 2

		Incident	Role	Impact level				Methods	Impacts		Status
2026-10-13	2026-10-26 12:51	Arcadia: unauthorized access to the SpeeCAN RAIDEN alert service	[Through a supplier]	[Major]	[Critical]	28 Arcadia, Inc., Takehara City, Aichi Prefectural Police, Chiba Prefectural Government, Fukuoka Prefectural Police, Hiroshima City, Hiroshima Prefectural Police, Hyogo Prefectural Police, Kagoshima Prefectural Police, Kanagawa Prefectural Police, Nagoya City, Oita Prefectural Government, Okayama Prefectural Police, Saitama City, Saitama Prefectural Police, Tochigi Prefectural Police, Chiba City, Fukuyama City, Hadano City, Hatsukaichi City, Oita City, Okazaki City, Yokosuka City, Ichikai Town, Kanuma City, Minamiboso City, Nasukarasuyama City, Shioya Town	Aichi, Chiba, Fukuoka, Hiroshima, Hyogo, Kagoshima, Kanagawa, Oita, Okayama, Osaka, Saitama, Tochigi	[Web app exploit]	[Data leak][Service outage]	3,136,000	[Investigating]
2020-03-12	2020-03-17 08:00	Minamiboso City Tourism Association: prize emails for a Minamiboso city coupon draw carried a list of 1,577 entrants	[Through a supplier]	[Moderate]	[Moderate]	2 Minamiboso City, Minamiboso City Tourism Association	Chiba	[Misdelivery]	[Data leak]	1,577	[Resolved]