已確認
Aichi Prefecture: contractor mis-sent 151 seminar applicants’ email addresses
On March 10, 2026 contractor Japan Research Institute sent a seminar notice to 151 applicants with To instead of Bcc; the prefecture disclosed on March 11.
日本：依國家或地區查詢資料外洩事件
依企業、國家、產業、發生年份和攻擊方式查詢事件，了解外洩資料、影響範圍、查證狀態、企業應對及來源。
調查中
Saison Fundex: leaseback customer data may have leaked via contractor Aoyama Main Kikaku ransomware
After contractor Aoyama Main Kikaku suffered ransomware on January 12, 2026, Saison Fundex disclosed on March 10 (updated June 1) that Saison leaseback customer data may be in scope.
已確認
Yamagata University: faculty ages left undeleted on website documents, 2,149 entries (with duplicates)
Faculty ages that should have been removed before publishing installation-plan documents were left on the website; disclosed March 10, 2026.
已確認
INPIT: contractor Shiga Invention Association mis-sent expert and external-director personal data
On February 26, 2026 the Shiga IP support-desk contractor emailed an expert list to external directors by mistake; INPIT disclosed on March 6.
調查中
White Essence Meguly: registrant personal data may have leaked after site intrusion
Possible data leak: After finding an intrusion on the Meguly job-site server on February 18, 2026, White Essence issued a first notice on March 6 and an April 17 update saying database theft was likely.
已確認
Marimo Holdings: group employee data leaked after officer-impersonation phishing
On December 18, 2025 a phishing mail impersonating a group officer led to unauthorised acquisition of some employee data including leavers; disclosed March 6, 2026.
調查中
Nihon University Sangenjaya: staff mailbox personal data may have been viewed after phishing takeover
On February 9, 2026 one staff mailbox was taken over via phishing and sent 321 suspicious messages; the campus disclosed on March 6 that mailbox personal data may have been viewed.
調查中
Tokyu Sekkei: third parties may have viewed related personal data after improper device use on public transport
Possible data leak: After a third-party report that a staff device screen was visible on public transport on February 27, 2026, the firm investigated and disclosed on March 3.
已確認
AMED: 459 email addresses (279 personally identifiable) leaked via misaddressed bulk mail
A bulk admin email used To instead of Bcc so addresses were visible among recipients; AMED disclosed this on March 3, 2026.
調查中
Kanehara Rinken Kokushi Online: 160 registrants’ emails and nicknames may have been publicly reachable
Possible data leak: On February 17, 2026 a leftover test file on production was found and closed the same day; disclosed March 3, with an April 17 update reporting no further intrusion traces.
調查中
Jiho group reports possible exposure of up to 890 email addresses
A compromised cloud-mail account may have allowed viewing or acquisition of address-book email addresses. Sending suspicious phishing emails is confirmed; data acquisition is not.
調查中
FABRIC TOKYO: other customers’ data may have been shown due to EC settings error
Possible data leak: From about 18:30 to 23:00 on February 18, 2026, a product-detail settings error could show the wrong customer data; disclosed on February 19. Not an intrusion.
調查中
JR Sendai Hospital: patient data of 11,791 people may have leaked after device losses
Possible data leak: After finding missing devices on February 3, 2026, the hospital issued a first notice on February 18 and later updates expanding the affected set to 11,791 people as of the June 15 update.
已確認
JOGMEC: names of 2,246 mining-right holders leaked after ex-staff removal of data
JOGMEC announced on February 17 that a former employee had taken outside personal data obtained while employed.
調查中
Miyazaki Prefecture: personal data of 102 people may have leaked after accounting documents went missing
Possible data leak: December accounting vouchers being returned to the Minaminaka agriculture office went missing and contain personal data of 102 people; disclosed on February 16.
已確認
Hokuto City: 586 Hokuto Fan Club member emails leaked via misaddressed mail
On February 13, 2026 a contractor sent fan-club event mail with To instead of Bcc so all member addresses were visible; the city disclosed this on February 14.
調查中
Komae City: voter-roll data of 69,244 people may have leaked after election SD-card loss
Possible data leak: Five SD cards used for voter-roll checks in the 8 Feb 2026 general election were found missing on February 10 and the city disclosed the loss.
調查中
Sekaimon reports possible leak of member and business-related information
Malware accompanied unauthorised access, with possible exposure of personal information in databases. The final investigation did not establish confirmed exfiltration.
調查中
GALA Yuzawa: customer data of up to 1,518 people may have leaked after server ransomware
GALA Yuzawa announced on February 12 that ransomware on some servers may have allowed customer personal data to leak externally.
調查中
Mynavi: user, partner and employee data may have leaked via cloud-service intrusion
After detecting an anomaly on a used cloud service on 5 Dec 2025 and confirming possible personal-data exposure on 16 Jan 2026, Mynavi issued a first notice on 12 Feb and later updates with category counts.