Photo/IllutrationOchanomizu University Junior High School in Tokyo’s Bunkyo Ward that Prince Hisahito attends. (Yohei Kobayakawa)

  • Photo/Illustraion

Police have beefed up security around Prince Hisahito at his junior high school in Tokyo after two knives were found placed on his desk on April 26 after he and his classmates had left their classroom, investigative sources said.

Security camera footage at Ochanomizu University Junior High School in Bunkyo Ward showed a middle-aged man in work clothes entering the school premises.

Police believe the man knew the layout of the school and crept into the prince's classroom when it was vacant after the students went to take another class, the sources said.

Hisahito, 12, is third in line to the Chrysanthemum Throne and the only grandson of Emperor Akihito and Empress Michiko. The incident followed Hisahito’s entry to the school earlier this month.

School officials reported to Tokyo’s Metropolitan Police Department on the evening of April 26 that they found two knives attached to a stick with tape placed between the prince’s desk and the desk next to it as if they were bridged between the two desks, the sources said.

The blades of the knives were painted pink.

The man apparently could identify Hisahito’s desk as each has the name of the student who sits there on it.

Apart from the knives, nothing was left on the desks, such as a paper claiming responsibility for the act, according to the sources.

A surveillance camera installed at the front gate of the school captured the man in bluish work clothes with a hard hat entering the school premises before noon.

He identified himself as a worker doing construction work to the school staff via the intercom.

Footage from a surveillance camera set up near the school building showed him entering it.

The knives were discovered in the afternoon shortly after Hisahito and other students had left the classroom.

Police plan to tighten security around the prince as a series of ceremonies are scheduled in the coming week with respect to Akihito’s abdication on April 30 and the ascension of Crown Prince Naruhito as emperor on May 1.