ミツカン（ミツカン365）Data breach / unauthorized access incident
- Occurred on
- October 30, 2021
- Announced on
- November 6, 2021
- Severity
- CLimited data such as email addresses and identifiers.
- Scale
- 487 people
- Main impact
- Member information on the members-only community site "ミツカン365" was tampered with: nicknames and icons for 487 people were altered, and customer IDs and email addresses for 29 of them were confirmed leaked.
- Information involved
- Email addressUser / member ID
- Cause / key point
- The incident is attributed to unauthorized access by a third party, but the intrusion route and specific techniques have not been disclosed.
- Industry
- Food & dining
- Last updated
- November 8, 2026
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Written & reviewed
Reviewed byYutaro SasaoFounder & CEO, MediaLeap Inc.
CEO of MediaLeap Inc. Working on both sides of web advertising and web media since 2013; founded the company in May 2025.
Review scope: cross-checking against primary sources (official and government announcements), verifying claims stay within the facts, and checking source attribution。Last reviewed:
Written by:Leak Watch editorial team (AI-assisted drafts verified against sources by the editorial team) · Reviewer profile · Request a correction
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Attack method classification: Unauthorized access (method undisclosed)(Breached, but the technique was not identified or disclosed)
Read the Unauthorized access (method undisclosed) guide and national trends →