Home › All Victims › Nostrum

Nostrum

thegentlemen

This record tracks a ransomware attack claimed by the thegentlemen group against Nostrum. It collects the publicly disclosed attack details — sector, location and timeline — as published on the operator's leak site and indexed by Breach House.

Window Zero

EXPOSURE GAP

Window Zero is the time the breach stayed in the open before anyone said so — the gap between when the attack was first discovered on the operator's leak site (t1) and when it was publicly disclosed (t2). The wider this window, the longer victims, staff and customers were exposed with no warning.

50days open
t1 · Published t2 · Pending
Apr 27, 2026Not disclosed yet
Country
Japan
Business Category
Retail / E-commerce
Employees
0-50
Discovered
2026-05-06
Published
April 27, 2026
Disclosed / Notified
Not disclosed yet
Victim ID
LJIL3ugDs1Ud

Attack Summary

nostrum.co.jp Nostrum Corporation, based in Japan, was founded in 1991 and specializes in smartphone app development, web system development, and website construction. The company is represented by Ryoichi Jono and is registered on the J-GoodTech platform as a verified Japanese technology business. One of their flagship self-developed products is a job aptitude test preparation tool — a simulation platform replicating real SPI, TG-WEB, and similar employment exam interfaces used by major Japanese companies

Leak Screenshots

SAMPLE

Proof-of-breach screenshots the operator posted from the stolen data. Previews are redacted and locked — the originals are available on HaveIBeenRansom.

file_tree.png
finance_2024.xlsx
passport_scan.jpg
contract_signed.pdf
Sign in or explore HaveIBeenRansom to view the full leak gallery.
View leak gallery →

Dark Web Exposure

Cross-referenced against HaveIBeenRansom's dark-web index of ransomware leaks, breaches & infostealer logs.
0
found in Infostealer logs
0
found in Traditional breaches
0
found in Ransomware leaks
Emails exposed
••••
Internal
•••
External
•••
Distinct leaks
••
••••••••••••••••••••••••
•••••••••• · ••••••
••• emails
••••••••••••••••••••••••
•••••••••• · ••••••
••• emails
••••••••••••••••••••••••
•••••••••• · ••••••
••• emails
••••••••••••••••••••••••
•••••••••• · ••••••
••• emails
Full exposure is locked
See every breached email, the internal-vs-external split and each leak source behind this victim.
Sign in to unlock Dig deeper on HaveIBeenRansom →
Want the complete picture — passwords, machines, full leak files? It's all searchable on HaveIBeenRansom.
Search this victim →
Visit Website View Group: thegentlemen

Related entries

Enciso Ltda South Texas Spinal Clinic Mahajak Development Calipage Humblet Ministarstvo zdravstva Republike Hrvatske Palmer Sicard
Legal Disclaimer: This ransomware victim record reflects information published on the operator's leak site. Breach.house does not acquire, download, host, access or redistribute unlawfully obtained data. It indexes only publicly visible information posted by ransomware, breach and infostealer operators and open web sources, without accessing the underlying stolen content. The service supports public awareness, legitimate research and cyber-resilience.