Tokyo police said Thursday they had arrested an engineer for allegedly stealing massive amounts of personal data from an educational services firm, a leak that may ultimately affect more than 20 million people.
Private details—including names, addresses, phone numbers and birthdays—were stolen by 39-year-old suspect Masaomi Matsuzaki, police said, with Japanese media reporting that he sold the information for about 2.5 million yen ($24,600).
The magnitude of the leak, which has been headline news in Japan, prompted angry calls for an explanation from Benesse, one of the country's best-known companies.
The firm, whose holdings include the Berlitz language education brand, offers services ranging from teaching babies how to use toys to English instruction.
Benesse said last week that it had confirmed the leak of personal data of at least 7.6 million people, but it added that the problem could ultimately affect more than 20 million.
However, other details such as credit card numbers, banking data and student performance evaluations were safe, it said.
Matsuzaki was a systems engineer at a Benesse affiliate when he allegedly copied personal details of customers who had supplied the information to the educational services company, according to police. They said a minimum of 10 million were affected.
The theft was discovered when people started receiving phone calls and advertising letters from Benesse rivals that should not have had the information, authorities said.
Explore further: S. Korea police arrest two over mass telecom data theft