Kim Jong-un has outright threatened to “sink” the island nation as he threatened Tokyo after firing two missiles over its northern-most island of Hokkaido.
Pyongyang has often placed Japan in its sights, and feels deep resentment over the empire’s 35-year occupation of Korea until 1945.
The Japanese are the one people in the world to have suffered from the horrors of nuclear war at the hands of the US.
Hiroshima and Nagasaki were nuked by American bombers to bring an end to World War 2 – killing around 225,000 people.
There are fears growing in the island nation this same thing could happen again – and the people of Tokyo are taking no chances, Daily Star Online can reveal.
The devastation North Korea could reap on Japan is far greater than the damage inflicted by the US.
Kim is feared to have nuclear bombs up to the strength of 250kt – more than 10 times as powerful than Washington’s bombs the Fat Man and the Little Boy.
Hiroshima and Nagasaki may be in Kim’s firing line, but the mad-dictator is also feared to strike other population centres in Japan such as Tokyo and Osaka.
“The four islands of the archipelago should be sunken into the sea by the nuclear bomb,” North Korea’s state media said.
Defence expert Harry Kazianis, director of defence studies at the Centre for the National Interest, told Daily Star Online the island nation will be undergoing a major upgrade of their missile defences to tackle the threat North Korea.
He said: “It is just going to be a question of how fast they can get it.”
Mr Kazianis said Japan may even consider deploying THAAD, the missile defence system which raised the fury of Kim in South Korea.
More PAC-3 missile defence launches and naval and land based weapons system Aegis may also be picked up by Tokyo, he added.
The expert said: “I think Japan is going to beef up its missile defence. They are going to need all this tech to take out these missiles.”
Hiroshima is believed to be under direct threat from North Korea, with a missile defence battery being rushed there earlier this year after Kim first tested an IBCM.
North Korea identified Hiroshima as one of the locations their missile may fly over should they choose to strike US bases in Guam.
Some argue the atomic bombing over Japan could be considered a war crime after the two devices were dropped on August 6 and August 9, 1945.
The threat has prompted Japan to consider going back on its “pacifist” defence policies, with Prime Minister Shinzo Abe considering up the nation’s defences and strike capability.
Japan’s defence plans, released earlier this year, reveal considerations for “preemptive strike” capability against North Korea.
Tensions in Japan have risen so high its military has deployed a missile defence battery beneath the flightpath of Kim’s weapons.
Japan’s defence minister has admitted they may consider shooting down the nuclear-mad despot’s missiles if they fly over Hokkaido
US President Donald Trump threatened North Korea this week as threatened to “totally destroy” the rogue state in a speech at the UN.