Prince Hisahito and his parents Prince Akishino and Princess Kiko pose for photos at Ochanomizu University junior high school in Tokyo. File / Koji Sasahara / AFP
Two kitchen knives have been found at the school desk of Japan's Prince Hisahito, grandson of Emperor Akihito, with security camera footage showing a suspicious man trespassing on the grounds, media reported on Saturday.
The incident comes as authorities are beefing up security ahead of the popular emperor's abdication next week after a 30-year reign.
Officials of the Tokyo junior high school found the knives on Friday at the desk used daily by the 12-year-old prince, public broadcaster NHK and other news reports said, quoting unnamed investigators.
Hisahito, who began attending the school this month, was not in the classroom when the knives are believed to have been left.
There were no reports of any injuries or damage at the school, the reports said, adding that police did not find any threatening note related to the case.
Security camera footage showed a man with a helmet trespassing on the school grounds at around noon, they said.
Police were searching for the middle-aged man who was dressed as a construction worker.
A police spokeswoman declined to comment while no immediate confirmation was available from the school.
Threats to the imperial family are relatively rare. In 1975, Akihito was almost hit by a Molotov cocktail in Okinawa, a major World War II battlefield where there was strong anti-emperor sentiment.
The incident comes as Japan is preparing for the abdication on Tuesday of Akihito, the first monarch to relinquish the throne of the world's oldest imperial family for two centuries.
Akihito's eldest son, 59-year-old Crown Prince Naruhito, will take the throne the following day in a series of ceremonies.
Hisahito is the son of Naruhito's younger brother and the last eligible male heir.
Japan's centuries-old succession would be broken if Hisahito does not have a male child as the Imperial Household Law, in place since 1947, does not allow women to ascend the Chrysanthemum Throne.
With skateboarding making its Olympic debut in Japan next year, Cuban skateboarders are hoping their sport will finally be accepted at home.
Yoshiro Mori announced his surprise resignation as honorary chairman of the Japan Rugby Football Union, officials said on Thursday, just months before the country hosts the World Cup.
Newly crowned Masters champion Tiger Woods announced on Thursday he will return to Japan for the first time in more than a decade to play in a new US PGA Tour event in October.
A French tourist has died after falling from a waterfall while trying to take a selfie in Thailand, police said on Friday. The accident happened on Thursday afternoon on the tropical island
A Cambodian judge has closed the investigation into treason charges against opposition leader Kem Sokha and that means he could now be brought to trial or the charges dropped,
The Hong Kong government condemned on Friday an attack by a “violent mob” on the city’s justice secretary in London, the first direct altercation between demonstrators and