As of September 29, 2026
[Update – Important] Notice of Possible Personal Information Leak Due to Unauthorized Access to Our Third Party Reservation Management System, and Request for Caution
Thank you for your continued patronage of THE MARK GRAND HOTEL.
We have recently been informed that unauthorized access has occurred in a third-party reservation management system the hotel uses (the site controller system “Temairazu”), and that guests’ personal information may have been viewed or leaked externally as a result.
We have already reported this matter to the Personal Information Protection Commission of Japan. In addition, security measures have been completed for the system component involved, and it is now operating normally and securely.
We would like to share the facts confirmed to date, along with important precautions we ask our guests to take.
■ Affected Reservations
Based on our investigation so far, we have confirmed that suspicious messages have been sent via the messaging app WhatsApp to guests with reservations that meet the following conditions:
Reservation date: Reservations made on or before September 21, 2026
Stay date: Reservations for stays on or after September 21, 2026
■ Regarding Credit Card Information
The reservation management system affected by this incident does not handle or store credit card information. Therefore, no credit card information has been directly leaked from our hotel nor the third party system.
The activity currently being reported is a phishing scheme, in which fraudulent messages are sent to contact information obtained through this incident, directing recipients to an external website and attempting to have them enter their credit card details there.
■ Request to Our Guests (Important Precautions)
Our hotel will never request urgent payment or ask you to re-enter credit card information via SNS (such as WhatsApp) or other messaging services.
If you receive a suspicious message requesting to be from our hotel or accommodation (by email, SMS, WhatsApp, etc.), please take the following precautions:
Do not click any URLs or links included in the message
Do not enter your credit card details or personal information
Do not reply to the suspicious message
Do not make any payment or money transfer as instructed in the message
If you wish to confirm your reservation details, please contact our hotel directly or the official support desk of the booking site you used
■ If You Have Already Entered Information or Made a Payment
If you have already entered your credit card details on a suspicious website, please contact your credit card company immediately to request that your card be suspended, in order to prevent unauthorized use by a third party.
In addition, to help us understand the scope of this situation, we would greatly appreciate it if you could also contact the emergency inquiry desk.
Temairazu Co., Ltd.
https://www.temairazu.co.jp/pdf/1206/news-update
Department: Emergency Response Desk
Email: helpdesk@temairazu.com
We sincerely apologize for the concern and inconvenience this may have caused you.
As of September 29, 2026
[Important] Notice Regarding the Possibility of Personal Information Leakage Due to Unauthorized Access to Our Hotel's Reservation Management System and a Warning to Our Guests
Thank you for your continued patronage of The Mark Grand Hotel.
We have recently discovered that our hotel's reservation management system (site controller "Temairazu") was subjected to unauthorized access by a third party, and that there is a possibility that customers' personal information may have been viewed or otherwise disclosed externally.
We have already submitted a report to the Personal Information Protection Commission regarding this matter. In addition, security measures for the affected system component have been completed, and it is now operating normally and securely.
Therefore, we would like to inform you of the facts currently confirmed and the matters for your attention.
■ Eligible Reservations
We have confirmed that suspicious messages were sent to some reservation holders whose bookings meet the following conditions.
Reservation date: Reservations confirmed by September 21, 2026.
For stays on or after September 21, 2026
■ About credit card information
The reservation management system that caused this issue does not handle or store credit card information.
Therefore, there is no evidence that credit card information was directly leaked from our hotel. The incident in question is a phishing attempt in which fake messages were sent to contacts whose information was obtained, trying to trick recipients into entering their credit card details on external websites.
Notes for Guests with Reservations (Important Information)
Our hotel will never contact you via social media (such as WhatsApp) or messaging services to request urgent payments or to re-enter your credit card information.
If you receive any suspicious communications (email, SMS, WhatsApp, etc.) claiming to be from our hotel or accommodation, please pay close attention to the following points.
Do not open any URLs or links included in the message.
Do not enter credit card information or personal information.
Do not reply to suspicious messages.
Do not follow the instructions in the message to make a payment or transfer money.
To confirm your reservation details, please contact the official customer service of the hotel or the booking website where you made your reservation.
In the event that you have accidentally entered your information and made a payment
In the unlikely event that you enter your credit card or other payment information on a suspicious website, please contact your credit card company immediately to consult with them and arrange to suspend the card and take any other necessary steps to prevent fraudulent use by a third party.
In addition, to help us understand the situation, we would be grateful if you could contact us at the inquiry desk listed below.
Temairazu Co., Ltd.
https://www.temairazu.co.jp/pdf/1206/news-update
Department in charge: Emergency Response Desk
メールアドレス：helpdesk@temairazu.com
We sincerely apologize for the worry and inconvenience this has caused our customers.