• Japanese power giant reveals it lost drive containing data of millions of clients
• Drive was left in an apparently unlocked cabinet
• Nearly 11 million clients at risk, but no bank or card data was affected

A Japanese energy giant has apologised after losing a physical storage drive containing the data on millions of its clients.

Workers for Kyushu Electric Power Co. apparently mislaid the drive, which had been left in an unlocked cabinet, the company explained in an official announcement.

The drive allegedly contained information on up to 10.9 million accounts, including customer names, electricity usage data, and telephone numbers - although the company said no bank account information or credit card data was stored.

Going AWOL

One of Japan's biggest regional utilities, Kyushu Electric Power Company supplies electricity across the Kyushu region, which has an overall population of around 12.5 million people, and includes major prefectures such as Fukuoka, Nagasaki, Kumamoto and Kagoshima.

In its announcement, the company explains that the IT staff regularly performs backups to manage server storage.

It added that due to capacity constraints, on April 27, 2026, an external storage device was used for the task.

This drive was then stored in a server room cabinet protected by multiple physical security layers - a location which only 57 people had access to.

However when IT staff went to retrieve the drive on May 26, they found that the cabinet had been left unlocked, and the driver was missing.

Kyushu Electric filed a police report on June 4, and the company says it has since conducted its own investigations, including interviewing all personnel who entered the server room - but the drive cannot be found.

“The company is investigating all possibilities, including unauthorized removal of the device, but it has not yet been located,” its announcement noted.

The incident has now been reported to Japan’s Personal Information Protection Commission and the relevant government authorities, with the Japanese Ministry of Economy, Trade, and Industry reportedly givingKyushu Electric until July 8 2026 to report all the details about the incident and the preventative measures taken.

Via Bleeping Computer

Follow TechRadar on Google News and add us as a preferred source to get our expert news, reviews, and opinion in your feeds.

Mike Moore is Deputy Editor at TechRadar Pro. He has worked as a B2B and B2C tech journalist for nearly a decade, including at one of the UK's leading national newspapers and fellow Future title ITProPortal, and when he's not keeping track of all the latest enterprise and workplace trends, can most likely be found watching, following or taking part in some kind of sport.