SHINDO4

Tokyo Metropolitan Tama General Medical Center

Tokyo Metropolitan Hospital Organization

Personal data153people

LEAK CONFIRMEDHealth / medical / treatment / Date of birthLoss · Investigating

Open in the live monitor ▶
Disclosed
Nov 13, 2025
Detected
Oct 20, 2025
Detection to disclosure
24 days
Leak
Leak confirmed
Type
Loss
Status
Investigating
Security spend
Not checked yet
Compensation
Not announced

What leaked

IdentityFull name, Date of birth, Gender
Account dataPatient ID number
Special-care dataSurgery date

How many

  • Gastric cancer surgery patients 153 people

Who is affected

  • Patients

Cause

Several anonymous letters said a USB memory stick in a hospital envelope had been found in a station restroom and contained patient data

Timeline

  1. Anonymous letter received; the same day a resident who had received printed patient data also contacted the hospital
  2. Date of the Security NEXT report

What you should do

  1. Health data can't be taken back. Don't answer blackmail; call the police (#9110) or the consumer hotline (188)
  2. Check the company's notice to see if you're affected

Lessons for companies

  1. Report to the PPC: preliminary in 3–5 days, final in 30 (60 if malicious)
  2. Run red teaming and AI-assisted hardening, and publish how much you invest

Sources