Fears of devastating earthquakes and tsunamis are giving way to concerns over atomic attack following multiple missile tests conducted by Pyongyang
A brief research trip to Japans north-east coast to witness the aftermath of the March 2011 tsunami was all that it took to persuade Yoshihiko Kurotori to build a shelter in his back garden.
His home in suburban Wakayama is just a kilometre from the stretch of Pacific coast that scientists say is likely to be struck by a powerful earthquake and tsunami in the coming decades, causing an estimated 320,000 deaths.
I saw the foundations of what had once been peoples homes and thought there and then that I needed to protect myself, Kurotori said. My neighbours asked me what on earth I was doing when the diggers arrived. They thought I was wasting my money, but you cant put a price on safety.
He opened the shelters heavy steel door to reveal a tiny room encased by steel-reinforced concrete walls of up to 35cm thick. The centrepiece is a Swiss-made 1.8m yen (12,200) ventilation unit designed to keep the shelters occupants alive while it filters out radioactive particles and nerve gases such as VX and sarin.
But today, it is the potential for a manmade disaster, not a natural calamity, that has convinced the retired teacher that he was right to part with almost 8m yen to build the tiny shelter.
Multiple missile tests conducted by North Korea this year, culminating in the launch of an intercontinental ballistic missile, have sparked alarm in Japan, and ushered in a flurry of civil defence activity not seen since the second world war.
Nine towns have conducted evacuation drills since North Korean missiles landed in the sea inside Japans exclusive economic zone in March, with around a dozen more expected to follow soon.
A 30-second government warning, aired on primetime TV, implores people to seek shelter in sturdy concrete buildings or flee underground in the event of an attack. Those stranded in their homes should hide behind sturdy objects, lie face down on the floor and stay away from windows.