NTT Docomo breach: personal information on up to about 300,000 customers leaked through the online shop and My docomo
NTT Docomo confirmed on November 5, 2026 that unauthorised access to the Docomo Online Shop and My docomo leaked personal information on up to about 300,000 customers, including names, addresses, dates of birth and phone numbers; whether payment card details were also leaked is still under investigation.
What happened
NTT Docomo, Japan’s largest mobile carrier, confirmed on November 5, 2026 that unauthorised access to two of its customer services — the Docomo Online Shop and My docomo, the site where customers manage their contracts — leaked the personal information of up to about 300,000 customers. The company says it confirmed the unauthorised access on November 4 and suspended both services for emergency maintenance from about 1:00 a.m. on November 5. Its first announcement that morning described a high likelihood of unauthorised external access with the cause and scope still under investigation; a second report later on November 5 confirmed that customer information had in fact leaked. The company is still investigating whether credit card information or My Number national identification numbers were also leaked, and says it will notify affected customers promptly as the details are established.
Who is affected
Customers of the Docomo Online Shop and My docomo, up to about 300,000 people. The leaked information includes names, addresses, dates of birth and mobile phone numbers. Docomo has not said that passwords were leaked, and it has not confirmed any leak of payment card details or My Number numbers — both are expressly still under investigation, so treat any report claiming they were taken as unconfirmed. The two services were taken offline for emergency maintenance while the investigation continues, so customers may also face disruption to online purchases and contract changes until Docomo announces a restoration.
How serious
The concrete risk is targeted phishing and impersonation aimed at Docomo customers, using real names, addresses, dates of birth and mobile numbers. Those four items are enough for a scammer to place a convincing call or text “from Docomo” about the breach itself — the classic follow-on is a fake security notice pushing the victim to enter a password or card number on a lookalike page, which is precisely the step Docomo is warning customers not to take in suspicious emails. Name, address, date of birth and phone number are also the standard answers to identity checks at other services, so affected customers should expect the data to be tried elsewhere. There is no confirmed loss of passwords or card numbers in this incident as the company reports it today; the danger is what the confirmed contact and identity details let an attacker attempt next.
What to do now
Wait for Docomo’s own notice about whether your information is included, and reach the company only through its official app, its official website typed in yourself, or a number you already have — never through a link or number supplied by an unexpected call, email or text about this breach. Do not enter a password or credit card details on any page a message sends you to; Docomo itself urges customers not to enter card information or passwords in suspicious emails. If a caller claims to be Docomo and asks you to confirm personal details, hang up and call back on the official number. Keep an eye on your mobile account for contract changes you did not request, and on bank and card statements while the payment-card question remains open.
Sources: SmartScope, November 5, 2026 (reporting NTT Docomo’s November 5 announcements, including the second report confirming the leak) · TV Asahi News, November 6, 2026 (reporting Docomo’s confirmed leak of up to about 300,000 records)