Data Breach at Yokosuka Gakuin: What You Need to Know

December 16, 2025
|In Data Breach
|By admin

In a disturbing turn of events, the Rhysida ransomware group has claimed responsibility for a data breach affecting Yokosuka Gakuin, a private co-educational institution in Yokosuka, Kanagawa Prefecture, Japan. This breach has raised concerns about the security of sensitive data and the potential implications for affected individuals.

About Rhysida Ransomware Targets Japan’s Yokosuka Gakuin

Yokosuka Gakuin, established in 1950, operates at multiple educational levels, including elementary, junior high, and high school, founded on Christian principles. As a reputable institution in Japan, the school’s data breach is particularly alarming, as it jeopardizes the privacy and security of students, staff, and faculty.

What Happened

The Rhysida ransomware group has publicly listed Yokosuka Gakuin on their data leak site, demanding a ransom of 6 BTC (Bitcoin) for the exclusive rights to the stolen data. The group has set a seven-day deadline for the school to comply, warning of the potential publication or sale of sensitive information if their demands are not met.

The compromised data reportedly includes:

  • Passport scans and identification documents
  • Life insurance deduction forms containing financial details
  • Handwritten application forms with personal contact information
  • Budget calculation requests and internal financial documents
  • Staff or faculty lists with names and addresses
  • Administrative records and receipts

This breach poses significant risks, especially given the nature of the information involved, which could be exploited for identity theft or financial fraud.

Next Steps

If you believe you are affected by this data breach or have concerns about your personal information being compromised, we encourage you to reach out to us at Srourian Law Firm (SLF). Our legal team is prepared to discuss your options and help you navigate the complexities of this situation. Protecting your rights and privacy is our top priority.

LINKS:

  1. https://slfla.com
  2. https://apps.calbar.ca.gov/attorney/Licensee/Detail/285678
Investigations > Data Breach at Yokosuka Gakuin: What You Need to Know
Data Breach at Yokosuka Gakuin: What You Need to Know

Srourian Law Firm is investigating a potential class action lawsuit against Rhysida Ransomware Targets Japan’s Yokosuka Gakuin for a recent data breach.

If you received a NOTICE OF DATA BREACH letter from Rhysida Ransomware Targets Japan’s Yokosuka Gakuin, complete the form below so we can discuss your legal options.

Submit Your Information

    X

    Submit Your Information

    Please review the terms below and sign to proceed

    You (“Client”) and SLF (“Attorney”) and hereby agree that Attorney will provide legal services to Client on the terms set forth below.

    1. SCOPE OF SERVICES. The legal services to be provided by Attorney to Client are as follows: Representation for claims in a class action lawsuit to be brought against pertaining to the data breach for which Client received notice. Attorney shall only represent Client only on the matter described. This Agreement does not apply to any other legal matters.

    2. FEE. Attorney shall only be compensated for legal services if a recovery is obtained for Client. If no recovery is obtained, Attorney shall receive no fee.

    3. COSTS AND OTHER CHARGES. Attorney is authorized to incur various litigation costs (including but not limited to court fees, attorney service fees, expert fees) while performing legal services under this Agreement. Attorney shall only be reimbursed for litigation costs if a recovery is obtained for Client. If no recovery is obtained, Attorney shall not be reimbursed costs.

    4. DUTIES OF CLASS REPRESENTATIVE. Client understands that this is a class action case for which he/she seeks to serve as class representative.

    1. A class representative represents the interests of all members of his/her class in litigation to recover money damages for the class.

    2. A class representative is not required to be particularly sophisticated or knowledgeable with respect to the subject of this lawsuit. However, he/she should be interested on a continuous basis in the progress of the lawsuit, and must make every effort to provide his/her lawyers and the court with all relevant facts of which he/she is aware.

    3. A class representative always considers the interest of the class as he/she would consider his/her own interests.

    4. A class representative recognizes and accepts that any resolution of the lawsuit, such as by settlement or dismissal, is subject to court approval, and must be designed in the best interests of the class as a whole.

    5. A class representative volunteers to represent many other people with similar claims and damages, because he/she believes that it is important that all benefit from the lawsuit equally, because he/she believes that a class lawsuit will save time, money, and effort, and thus will benefit all parties, and the court, and because he/she believes that the class action is an important tool to assure honesty in the marketplace and compliance with the law.

    6. A class member has claims, which are typical of those of the class, and thus involve common issues of law or of fact. For example, as a class representative, your claims against the defendants are typical of the class claims against them.

    7. A class representative participates in the lawsuit, such as testifying at deposition and trial, and assisting counsel in accurately answering written interrogatories, any by keeping generally aware of the status and progress of the lawsuit.

    5. RESPONSIBILITIES OF ATTORNEY AND CLIENT.  Client agrees to be truthful with Attorney, to cooperate, to keep Attorney informed of any information or developments which may come to Client’s attention, to abide by this Agreement, and to keep Attorney advised of Client’s address, telephone number and whereabouts.  Client will assist Attorney in providing necessary information and documents and will appear when necessary at legal proceedings. Attorney shall perform the legal services called for under this Agreement and will keep Client informed of Attorney’s progress in their efforts to obtain resolution of the claims/lawsuit. Attorney shall prosecute the claims/lawsuit through arbitration/mediation and/or trial and verdict. Attorney shall not represent Client on any appeal or any proceeding to execute/collect a judgment.

    6. FEE CALCULATION. Attorney will keep time records for time spent litigating the matter. If recovery is obtained for the Class, Attorney intends on submitting time records to the Court in support of an award of attorneys’ fees. Attorney shall only receive what is approved and awarded by the Court. 

    7. SERVICE AWARD. If a recovery is obtained for the Class, Attorney agrees to petition the Court for a payment to Client to compensate Client for serving as class representative and conferring benefit on the Class through the commitment of time in the prosecution of the lawsuit. This is commonly known as a “service award,” and is payable only upon Order of the Court. Client acknowledges that a service award has not been promised to the Client, does not form the basis for Client’s decision to act as Class Representative, and that no other benefits or payments have been promised to Client. In some instances, following the filing of a class action lawsuit, the lawsuit cannot proceed on a class basis. This occurs, for example, if Client has signed an arbitration agreement that gives up the ability to sue in court on a class basis. In such instances, Client authorizes Attorney to seek individual (non-class) settlement of Client’s individual claims. If Attorney negotiates an individual settlement of Client’s individual claims, Client understands that Attorney will use time records to negotiate attorneys’ fees separate and apart from whatever is negotiated for Client’s individual claims.

    8. JOINT REPRESENTATION.  Client understands and acknowledges that proceeding on a group basis or class action with other class members (“claimants”) is the only economical basis for prosecuting the subject claims. Because representing all claimants simultaneously in the same matter creates potential conflict of interest, Client has considered, acknowledges and accepts the following potential risks:

    1. Joint representation necessarily requires a balancing of interests instead of vigorously asserting any one claimant’s interest on an issue, which could lead to results less favorable than might be obtained if Client were represented separately;

    2. There is no attorney-client privilege as among jointly represented claimants with regard to the subject of the joint representation. If each claimant were separately represented, each such claimant would be free to instruct his or her attorney to refrain from disclosing communications between the claimants and his or her attorney to other claimants and Attorney involved in litigation;

    3. Conflicts may arise if the claimants develop inconsistent strategies during the course of the litigation and/or Attorney receives conflicting instructions form the jointly represented claimants. While Attorney believes that the objectives of all the claimants are presently consistent, no two claimants may have exactly the same personal circumstances or needs, and a conflict, if unresolved, could require Attorney to withdraw from representing the group;

    4. Changing counsel in the midst of litigation can be expensive and detrimental to Client’s interests; and

    5. If Client for any reason has a claim against another of the claimants, Attorney cannot represent or advise either party with respect to such claim and separate counsel should be consulted.
      Client has considered the foregoing risks and weighed them against the benefits of proceeding on a group basis and, by signing below, acknowledges and accepts joint representation by Attorney.

    9. SETTLEMENT.  Client appoints Attorney as his/her attorney-in-fact to execute any and all settlements, drafts, and checks which Client could properly execute, so as to receive in Client’s name, any monies payable to Client; and Client authorizes Attorney to deposit same in Attorney’s trust account.

    10. NO OBLIGATION TO FILE LAWSUIT OR USE CLIENT AS NAMED PLAINTIFF. This Agreement does not obligate Attorney to file any lawsuit that Attorney, in its professional judgment, concludes does not have merit, or cannot be successfully pursued at reasonable expense. In addition, Attorney may, in its professional judgment, decide not to use Client as a class representative in class action litigation on behalf of the Potential Class, but instead to use another member(s) of the Potential Class as a class representative(s), in which event Client would have neither the rights nor the obligations associated with being a Class Representative.

    11. ATTORNEY’S RIGHT TO DISMISS LAWSUIT. In the event Attorney determines in its professional judgment, after filing a lawsuit in which Client is a class representative, that Client’s claim no longer has merit, or that it is in the Potential Class’ best interest for Client to no longer be a class representative, Counsel shall notify Client of that determination, and Counsel shall be permitted to dismiss Client’s individual Claim without prejudice, preserving Client’s individual Claim.

    12. DISCHARGE AND WITHDRAWAL.  Client may discharge Attorney at any time, upon written notice to Attorney.  Attorney may withdraw with Client’s consent, upon court approval, or if no court action has been filed, for good cause and upon written notice to Client.  Good cause includes Attorney’s determination not to pursue Client’s claim after initial investigation and research, Client’s breach of this Agreement, or Client’s refusal to cooperate or to follow Attorney’s advice on a material matter or any fact or circumstance that would render Attorney’s continuing representation unlawful or unethical. Client understands that Attorney’s representation will start with factual investigation and legal research regarding the client’s claim. If Attorney determine after appropriate investigation and research that it is not practical or reasonable to pursue client’s claim, Attorney will have good cause for withdrawal from representation of client.

    13. CONSENT TO JOINTLY PROSECUTE/OBTAIN LOCAL COUNSEL. Client expressly consents to Attorney associating with other law firm(s) to jointly prosecute the matter in a court of appropriate jurisdiction and/or act as local counsel. Client understands that Attorney is not licensed in any state outside of California, and also understands that Attorney can arrange for another law firm to act as local counsel and file a motion to admit Attorney into a foreign jurisdiction for the limited purpose of prosecuting the matter described in Paragraph 1.  Such an arrangement will not result in any increase of Attorney’s fees payable under this Agreement under any circumstance.

    14. PRESERVATION OF EVIDENCE. Client acknowledges and agrees to take all reasonable steps to preserve any and all documents, records, communications, and electronically stored information (including emails, text messages, and digital files) that may be relevant to the subject matter of this representation, including but not limited to any information related to the underlying incident or data breach. This duty to preserve applies regardless of whether the materials are stored physically or electronically and remains in effect throughout the duration of the attorney-client relationship and any related legal proceedings. Failure to preserve relevant evidence may adversely impact the Client’s case and could result in court sanctions.

    15. DISCLAIMER OF GUARANTEE AND ESTIMATES.  Nothing in this Agreement and nothing in Attorney’s statements to Client will be construed as a promise or guarantee about the outcome of the matter.  Attorney makes no such promises or guarantees, and cannot promise that the case will resolve in client’s favor through settlement or trial. Attorney’s comments about the outcome of the matter are expressions of opinion only.

    16. ENTIRE AGREEMENT.  This Agreement contains the entire agreement of the parties.  No other agreement, statement, or promise made on or before the effective date of this Agreement will be binding on the parties.

    17. COUNTERPARTS AS ORIGINALS. This Agreement may be executed in one or more counterparts, each of which shall be deemed an original, and which taken together shall constitute one and the same instrument and Agreement. A photocopy, facsimile transmission or JPG/PDF signed counterpart may be used as originals for all purposes for which an original may be used.

    18.MODIFICATION BY SUBSEQUENT AGREEMENT.  This Agreement may be modified by subsequent agreement of the parties only by an instrument in writing signed by both of them.

    Please Sign Below to Confirm