Daiki Suisan says app breach may have exposed data of 174,933 people
In short
Daiki Suisan, a kaiten sushi chain based in Sakai, Osaka, said its official smartphone app was hit by unauthorized access and the personal data of up to 174,933 people, including former users, may have leaked. The company said the access was identified on Sept. 15 and that it has not confirmed any actual external leak or misuse of the data. It is urging users to be wary of suspicious emails, messages and calls, and says it will never ask for passwords or verification codes.
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Daiki Suisan, a kaiten sushi chain headquartered in Sakai, Osaka, announced on Oct. 5 that its official smartphone app system had been accessed without authorization and that the personal information of up to 174,933 people, including users who have since cancelled their accounts, may have leaked. NHK News put the figure at about 175,000 people. [ 1 , 2 , 4 ]
According to the company, the data that may have been exposed includes names, phone numbers, email addresses, gender and postal codes, as well as addresses and dates of birth that were registered optionally, meaning not all users are affected by every item. The affected registrations were made between Nov. 1, 2024 and Sept. 15, 2026. Passwords, the company said, are managed on a separate server and are not among the potentially exposed data. [ 1 , 4 ]
Daiki Suisan said the unauthorized access was identified on Sept. 15. The company said it has strengthened its security measures and monitoring system, and that as of the announcement it had not confirmed that personal information was actually taken outside the company or that it had been misused. Nikkei reported that an external specialist company is also conducting an investigation. [ 1 , 4 ]
The company called on users to be cautious about suspicious emails, SMS messages and phone calls, and said it will not ask anyone to enter passwords or authentication codes in connection with this matter. [ 1 ]
Daiki Suisan was founded in 1975 as a wholesaler of dried fish and later expanded into retailing and kaiten sushi. It operates about 80 restaurants and shops, mainly in the Kinki region, including the Daiki Suisan Kaiten Sushi chain and the fish retailer Machi no Minato. [ 1 ]
Why it matters
The company operates about 80 restaurants and shops, mainly in the Kinki region, so the potential exposure affects a large share of its registered app users, including people who have since cancelled their accounts. With no misuse confirmed, the immediate consequence for customers is heightened risk of phishing attempts, which the company itself has flagged.
Key facts
- Daiki Suisan announced on Oct. 5 that its official app system was accessed without authorization and that personal information of up to 174,933 people, including former users, may have leaked. [ 1 , 2 , 4 ]
- Potentially exposed data includes names, phone numbers, email addresses, gender, postal codes, and optionally registered addresses and dates of birth. [ 1 , 4 ]
- Passwords were managed on a separate server and are not included in the potentially exposed data, according to the company. [ 1 ]
- The affected users registered with the app between Nov. 1, 2024 and Sept. 15, 2026, the company said. [ 1 , 4 ]
- Daiki Suisan said the unauthorized access was identified on Sept. 15. [ 1 , 4 ]
- The company said that as of the announcement it had not confirmed that the data was actually leaked outside the company or that it had been misused. [ 1 , 2 , 4 ]
- The company said it has strengthened security measures and monitoring and is warning users about suspicious emails, SMS messages and phone calls; it said it will not ask for passwords or authentication codes. [ 1 ]
- Daiki Suisan is headquartered in Sakai, Osaka, was founded in 1975 as a dried-fish wholesaler, and operates about 80 restaurants and shops, mainly in the Kinki region. [ 1 ]
Confirmed by several sources
- Daiki Suisan announced on Oct. 5 that its official app system suffered unauthorized access and that the personal information of 174,933 people may have leaked. [ 1 , 2 , 4 ]
- The company said no actual external leak or misuse of the data has been confirmed so far. [ 1 , 2 , 4 ]
- The potentially exposed data includes names and other personal details of app registrants, including former users. [ 1 , 4 ]
Still unclear
- Whether personal information was actually taken outside the company and whether it has been misused. The company said it has not confirmed any actual external leak or misuse, so the extent of real-world exposure remains unknown.
- What caused the unauthorized access and who was behind it. None of the documents state a cause or identify any party.
- Whether an external specialist company is investigating. Nikkei reported that an outside specialist firm is conducting an investigation; the other documents do not mention this, so it is a single-source detail.
What local media are saying
Timeline, local time
- Unauthorized access to the Daiki Suisan official app system is identified, according to the company (date only; no time given in the documents). [ 1 , 4 ]
- ITmedia reports the company's announcement, including the figure of 174,933 potentially affected people. [ 1 ]
- NHK News reports the company's announcement, saying about 175,000 people may be affected. [ 2 ]
- Nikkei reports the announcement and says an external specialist company is investigating. [ 4 ]