A Japanese department store discovered a golden teacup worth over 10 million yen ($65,000) had been stolen on Thursday, after it was showcased in an unlocked box.

The teacup, made of pure 24-carat gold, went missing from a Tokyo outlet of the major department store chain Takashimaya, where an event displaying an array of gold items for sale is being held.

The stolen teacup was one of the most expensive among over 1,000 pieces of shining teaware, tableware and artefacts on display, a Takashimaya spokesman told AFP.

"It was kept in an unlocked transparent box at the time, so it could be taken out easily for customers to take a close look," the spokesman said.

Security footage showed a man stowing the cup in his bag and fleeing the scene, local media reported, with police seeking the apparent culprit.

The display will continue but Takashimaya will firm up its security, the spokesman said.

The incident came a few months after Takashimaya officials were left red-faced over a fiasco surrounding $40 Christmas cakes in December.

Many of these strawberry-topped cakes, sold online and supposed to be immaculately decorated, were delivered to customers so mangled that the company was forced to publicly apologise and promise reimbursement.