Police called after thieves removed a safe in three minutes – a lesson in stealth and speed that any ninja would recognise

A museum devoted to the craft of the ninja – the covert agents of feudal Japan – has been left red-faced after thieves broke in and made off with a heavy safe containing more than 1 million yen (£7,155) in cash, all in the space of a few minutes.

Staff at the Iga-ryu Ninja museum in the central prefecture of Mie, called police after the building’s alarm went off in the early hours of Monday morning. But by then it appears that the culprits had already made their getaway.

Related: Ninja boom: how Japan's secret warriors swapped the shadows for the spotlight