With Japan expecting to welcome a record 40 million visitors in 2020, including for the Summer Games, immigration authorities are strengthening security to manage the influx and prevent abuse of their policies.

"We need to enhance measures to prevent any terror attacks," said Shoko Sasaki, chief of the Immigration Services Agency. Sasaki was referring to attacks including the 1972 Munich massacre, in which Palestinian group Black September stormed the Olympic Village and killed 11 Israeli athletes and a West German police officer during the Summer Games.

"We're doing our utmost to prevent such incidents with a sense of vigilance," she added, "because we don't want to allow anything like that to happen in Tokyo."