The communist state may carry out its third ICBM test today, according to South Korean intelligence.
Emboldened by its sixth and largest nuclear test last month, the rogue nation may fire another ICBM towards Japan, analysts believe.
Speaking on Monday, Japanese Prime Minister Shinzo Abe said: “There is a possibility of further provocations.
“We need to remain extremely vigilant and do everything we can to ensure the safety of our people."
Around 38,000 long-term Japanese residents and 19,000 tourists currently reside in Japan, Nikkei reports.
Evacuation measures have been put in place in anticipation of a US “military strike against North Korea”, a Japanese government source said.
The source said: “If the US decided on a military strike against the North, the Japanese government would start moving toward an evacuation on its own accord regardless of whether the American plans are public.”
A four-tier emergency plan has been put in place by Tokyo in the event a conflict breaks out on the Korean peninsula.
Seoul has agreed to give Japanese citizens access to safe zones, such as designated subway stations, churches and shopping malls, according to a Japanese source.
Fears of a conflict in the region are high after Donald Trump threatened North Korea with “fire and fury” over its missile tests.
The US President has ordered his military to “shoot down” North Korean missiles fired towards the US, according to reports.
Around 600 US soldiers and aircraft have arrived in Japan amid fears North Korea may risk war by firing another ballistic missile.