TOKYO -- A former employee of Japan's largest bank accused of stealing millions of dollars' worth of cash and valuables from customers' safe deposit boxes moved other customers' keepings to cover what was missing and delay detection, Mainichi Shimbun reporting has revealed.

The Metropolitan Police Department (MPD) believes the former employee of MUFG Bank Ltd., a woman in her 40s, falsified balances for the amounts of cash it stored to delay discovery of the thefts.

The woman allegedly stole from deposit boxes at branches within metropolitan Tokyo. She is thought to have repeatedly pilfered cash and other valuables at the Nerima and Tamagawa branches she worked at between April 2020 and October 2024. The losses are believed to lie somewhere between 1 and 2 billion yen (about $6.3 million-$12.6 million) at a minimum, affecting at least 60 customers.

According to an investigative source, most of the thefts were of cash. The ex-worker reportedly shifted money from other customers' deposit boxes when the customers she allegedly stole from visited the branches in an apparent bid to delay discovery.

The suspect kept detailed notes on the movements of customers' valuables. The MPD has obtained these and is investigating her on suspicion of larceny. She is believed to have used the stolen goods to invest in foreign currency exchange and other transactions.

According to MUFG Bank and other sources, the suspected thief had worked as a sales manager and it is thought that the work involving safety deposit boxes was solely left up to her. Spare keys were kept in the branches in case customers lost them, and the woman apparently used these to open the boxes without permission.

The woman was fired as a disciplinary measure in November 2024. The bank plans to improve its measures regarding backup keys to prevent similar incidents. It intends to move the keys from respective branches to the headquarters all together by the end of January and to institute a system of checks by multiple people.

(Japanese original by Ryo Endo, Tokyo City News Department)