SHINDO2

CKC Network Co., Ltd.

RansomwareSize not disclosed

POSSIBLE LEAKFull name / Phone numberInvestigating

Open in the live monitor ▶
Disclosed
May 15, 2026
Detected
May 2, 2026
Detection to disclosure
13 days
Leak
Leak possible
Type
Ransomware
Status
Investigating
Security spend
Not checked yet
Compensation
Not announced

What leaked

IdentityChild's name in hiragana, Some names in kanji
Account dataSchool grade at the time of inquiry
Transactions & activityLearning consultation and inquiry content
ContactPhone number (possible), Email address (possible)

Not leaked

  • Learning and member systems for current students run on separate servers and are not affected

Who is affected

  • People who inquired about cram schools and home tutoring (children and parents)

Cause

Ransomware attack by a third party

Timeline

  1. Ransomware attack on a server detected
  2. First report
  3. Reported to and consulted Aichi Prefectural Police
  4. First disclosure

Response

  • Service stopped
  • Forensic investigation

Shut down the server and preserved data; investigating cause and scope with an outside firm

What you should do

  1. Don't open links in emails from this company. The apology email itself may be fake
  2. Treat refund or apology calls and texts as scams. Call back only on the number from the official site
  3. Check the company's notice to see if you're affected

Lessons for companies

  1. Offline backups with restore drills; segment the network
  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