SHINDO2

Hotel Monterey Osaka

Hotel Monterey

Guest names59people

POSSIBLE LEAKFull name / Card numberImproper disposal · Closed (final report)

Open in the live monitor ▶
Disclosed
Jan 15, 2026
Detected
Dec 5, 2025
Detection to disclosure
41 days
Leak
Leak possible
Type
Improper disposal
Status
Closed (final report)
Security spend
Not checked yet
Compensation
Not announced

What leaked

IdentityNames in Roman letters (58) and in a foreign script (1)
Financial & paymentCredit card numbers on sales slips with six digits masked (7 people)

Not leaked

  • Full credit card numbers were not included

How many

  • Guest names 59 people
  • Credit card numbers 7 people

Who is affected

  • Hotel guests

Cause

The documents were most likely discarded by mistake together with other papers

Timeline

  1. Detected
  2. Reported to authority
  3. Security NEXT report date

Response

  • Notified individuals

Contacted guests whose card numbers were involved individually with an explanation and an apology

What you should do

  1. Even the last 4 digits make a scam call sound genuine. Never give card details by phone or text
  2. Check the company's notice to see if you're affected

Lessons for companies

  1. Don't keep ID or bank data: delete after checks or use a KYC provider
  2. Report to the PPC: preliminary in 3–5 days, final in 30 (60 if malicious)
  3. Run red teaming and AI-assisted hardening, and publish how much you invest

Sources