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Japan: Data Breach Incidents by Country / region

Search incidents by company, country, industry, year and attack method. Review affected data, impact, verification status, company responses and sources.

Country / region: JapanReset
767 results
CardsTable
Title / subjectOrganizationsVerificationReported impactDisclosed
Hiroshima Gas: investigating possible customer-data impact from Ryomo Systems intrusion広島ガスInvestigatingUnknown2026-09-30
Shudo Gakuen: server intrusion may have exposed staff/student personal and bank-account data修道学園InvestigatingUnknown2026-09-30
QUO Card: LINE official-account campaign system intrusion may have exposed display names and prize infoクオカードInvestigatingUnknown2026-09-29
TOPPAN: mis-sent Sompo Japan premium-deduction contractor list covering 177,426 policyholders to another insurerTOPPANConfirmed177,426 People2026-09-29
Fukuoka Pref.: misposted kaigo-certification application file left personal data on 183 officers viewable福岡県Confirmed183 People2026-09-29
Seicomart: app-mediated intrusion into member servers led to viewing of 574,647 club members’ dataセイコーマートConfirmed574,647 People2026-09-29
Unirita: intrusion into in-house document system led to theft of customer and employee dataユニリタConfirmedUnknown2026-09-29
Nagoya City: mis-attached Excel on an air-survey notice exposed contact data for 572 business sites for about an hour名古屋市Confirmed572 Records2026-09-29
Yamato Transport: about 5.26 million deferred-payment customer records exfiltratedヤマト運輸ConfirmedUnknown2026-09-29
Temairazu: TEMAIRAZU intrusion may have led to viewing/acquisition of guest reservation data手間いらずInvestigatingUnknown2026-09-28
Lean on Me: Metabase vulnerability abuse led to theft of personal data on 82,723 peopleLean on MeConfirmed82,723 People2026-09-28
Shueisha: data of 2,835 bloggers leaked from HAPPY PLUS COMMUNITY system集英社Confirmed2,835 People2026-09-28
Nagano Toshi Gas: Ryomo Systems intrusion may have exposed customer personal data長野都市ガスInvestigatingUnknown2026-09-28
Isesaki City: Ryomo tablet-support intrusion may have exposed 3,789 student account records伊勢崎市Investigating3,789 Records2026-09-28
Saga University: personal data may have leaked after ransomware hit admin NAS (about 80,000 people; patient data under review)佐賀大学InvestigatingUnknown2026-09-28
Daito Gas: Ryomo Systems intrusion may have exposed about 124,000 customers’ data大東ガスInvestigatingUnknown2026-09-28
Starts Publishing: OZmall intrusion may have exposed email (and some name/prefecture) for up to 442,779 membersスターツ出版InvestigatingUnknown2026-09-27
Keio Corporation: ransomware outage; possible exfiltration of customer and confidential data under investigation京王電鉄InvestigatingUnknown2026-09-26
LEGOLAND Japan: Amadeus hotel-booking platform intrusion hit contact data on 1,557 reservationsLEGOLAND JapanConfirmed1,557 Records2026-09-25
Izutsu Maisen: ApplyNow intrusion leaked part-time applicant personal data井筒まい泉ConfirmedUnknown2026-09-25