Japanese authorities are investigating after a drone landed on the roof of the prime minister's office.
No injuries or damage were reported. Premier Shinzo Abe was on a visit to Indonesia to attend the Asia-African conference when the small drone was discovered on the Tokyo building.
Police said it was not immediately known who was responsible. They are investigating the possibility it had crashed during a flight.
Public television NHK footages showed dozens of police and officials around the drone, which was covered by a blue tarpaulin.
NHK said the drone was about 50 centimetres (1.7ft) in diameter and had four propellers, carrying a small camera and something that looked like a flare. It was also decorated with a symbol that warns of radioactive material.
It was discovered by an official who was taking new employees on a tour of the prime minister's office in central Tokyo, according to reports.
Small drones are becoming increasingly popular in Japan and are often used for performances, aerial filming and other purposes. But they have raised safety and privacy concerns.
Japanese aviation laws have no restrictions for flying unmanned equipment at or below 820 feet above ground, except for flight routes.