Was MEDICUS SHUPPAN hit by ransomware?

MEDICUS SHUPPAN was listed by the thegentlemen ransomware operation (Japan), and stolen data was published on the group's leak site. Darkfield tracks this disclosure with the original leak post, screenshot and group context.

Who is the thegentlemen ransomware group?

thegentlemen is a ransomware operator tracked by Darkfield. See the full operator dossier for its known victims, sectors targeted, IOCs and leak-site infrastructure.

What data was leaked in the MEDICUS SHUPPAN breach?

thegentlemen published data attributed to MEDICUS SHUPPAN. Darkfield captured the leak post and a screenshot of the listing.

Ransomware victim disclosure

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メディカ出版 (Medica Shuppan Co., Ltd.)

listed as MEDICUS SHUPPAN · Claimed by Thegentlemen · listed 3 months ago

Age

since listed · data leaked

Status timeline

ListedMar 21, 2026
Data leakeddate unknown

At a glance

Group: Thegentlemen
Status: Data leaked
Country: Japan
Sector: Healthcare
Listed on leak site: Mar 21, 2026

About the victim

AI dossier — public-source company profile

Medica Shuppan (メディカ出版) is a Japanese publishing company specialising in educational content, books, seminars, and digital media for healthcare professionals. The company operates an online store and content-streaming service aimed at supporting the learning and professional development of medical practitioners in Japan. It also engages in advertising and marketing services directed at the healthcare sector.

Industry: Medical & Healthcare Publishing

Attack summary

Severity: high — Data has been confirmed published by the threat actor, and the victim company's own website acknowledges a ransomware incident. The company handles data relating to healthcare professionals and potentially subscribers/customers, making exfiltration of PII and business data a significant concern. While medical records per se are unlikely (publisher, not provider), the confirmed data publication and healthcare-sector context elevate severity to high.

The ransomware group 'thegentlemen' claims an attack on Medica Shuppan, with the victim's own public website confirming a ransomware (unauthorised access) incident as of May 2026 and reporting on investigation results and recurrence-prevention measures. The disclosed status indicates data has been published, though the specific data types and volume are not enumerated in the available post.

high

Data the group says was taken

AI dossier — extracted from the leak post

Internal business data
Potentially author/contributor records
Potentially customer/subscriber PII
Potentially healthcare professional contact data

What the group claims

medica.co.jp zoominfo.com/c/medicus-shuppan-co-ltd/463963337 is dedicated to providing enjoyable learning experiences for healthcare professionals through a variety of products and services, including seminar books and digital content. The company aims to support the education of medical practitioners and contribute to the future of healthcare. They also focus on sustainability and creating valuable content that serves as a backbone in the medical field. Their intended clients include healthcare professionals, authors, and bookstores

The leak post

captured from the group's site

Gentlecloud Protection 🛡️ Gentlecloud Verifying your browser... Initializing security checks... I'm not a bot

Sources

Victim sitemedica.co.jp
Leak posthttp://tezwsse5czllksjb7cwp65rvnk4oobmzti2znn42i43bjdfd2prqqkad.onion

Source

Indexed 3 months ago

This page surfaces a public ransomware disclosure indexed by Darkfield. Original posts come from the operator's own leak site; we cross-check against ransomware.live, RansomLook and RansomWatch where applicable. Share this URL freely.

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Disclosure context

About thegentlemen

thegentlemen is a ransomware group that emerged in September 2025, operating with apparent financial motivations based on their broad targeting of commercial sectors. The group has documented 267 victims across multiple countries, with primary focus on the United States, Thailand, France, Brazil, and India. Their targeting strategy demonstrates a preference for high-value sectors including manufacturing, technology, healthcare, and financial services organizations. Given the group's recent emergence and limited public documentation from established threat intelligence sources such as CISA, FBI, or major security research firms, specific details regarding their country of origin, operational structure, attack methodologies, encryption techniques, and whether they employ ransomware-as-a-service models remain unclear. The relatively high victim count of 267 in a short operational timeframe since September 2025 suggests either an aggressive campaign pace or potential inflation of victim numbers through affiliate operations, though without corroborating intelligence reports, the group's exact operational capabilities and notable campaigns cannot be definitively established. Current intelligence indicates the group remains active as of late 2025, though comprehensive threat profiling requires additional validated reporting from authoritative cybersecurity sources. The group has been linked to 483 public disclosures across our corpus. First observed on a leak site on September 9, 2025; most recent post June 11, 2026. The operation is currently active.

Also tracked as: the gentlemen.

Timeline of this disclosure

March 21, 2026MEDICUS SHUPPAN listed by thegentlemenon the group's public leak site

Other recent disclosures by thegentlemen

thegentlemen has been linked to 483 public victims on Darkfield. A sample of the most recent:

See the full thegentlemen dossier →

Sector and geography

This disclosure adds to ransomware activity in the Healthcare sector, which has 1,780 disclosures indexed across all operators we track. Geographically, MEDICUS SHUPPAN is reported in Japan, a country with 108 ransomware disclosures in our corpus.

If your organisation is affected

A listing by thegentlemen means MEDICUS SHUPPAN appeared on a ransomware extortion site and data attributed to it has been published. If this is your organisation, or a supplier you depend on, the priority is to confirm the intrusion and contain it before the window to act closes.

Engage your incident-response team and preserve forensic evidence before remediating — do not wipe affected systems first.
Force a password reset and revoke active sessions for exposed accounts; rotate any credentials, API keys or certificates that may have been in the stolen data.
Assess regulatory notification duties (GDPR, NIS2, sector regulators) — many carry a 72-hour reporting clock from awareness.
Monitor for the data appearing on thegentlemen's leak site and across paste and breach channels, and brief downstream partners who may be exposed through you.

How we know this. Darkfield monitors public ransomware leak sites continuously, archiving every new disclosure and the data later released against the victim. Each entry on this page is sourced from the operator's own publication and cross-checked against complementary OSINT feeds (RansomLook, ransomware.live, RansomWatch). We do not collect or host stolen data — only the metadata, timestamps and screenshots needed to make the public disclosure searchable and accountable. Records here are corrected when the original post is edited, retracted, or merged with another disclosure.