JAPAN: Few people are angrier that North Korea has joined the world's nuclear club than Sunao Tsuboi. As a 20-year-old Hiroshima student, he was burnt from head to toe when the US dropped the Fat Man A-bomb on that city in August 1945. He still bears the scars all over his face and body.
"We're furious about this test," he says of Japan's 270,000 A-bomb survivors. "It means that more countries are sure to follow, and how can the nuclear powers tell them not to develop their own bombs? Our greatest worry is that Japan will now feel it has to have its own nuclear weapon."
Japan's legacy as the world's only A-bomb victim means any talk of developing its own nuclear option has long been taboo. But in the wake of Pyongyang's apparently successful test, the limits of this taboo are again being tested.
Former prime minister Yasuhiro Nakasone is just the latest politician to suggest that Japan should "study the nuclear issue", voicing a sentiment that has long stalked the conservative wing of Japanese politics.
This week Japan's largest newspaper, the Yomiuri, also said the country should reconsider its aversion to the bomb, urging the government to not let its "emotional nuclear allergy" stop it from "taking a realistic response to such a major change".
Politics, not technology, hinders the development of Japanese nuclear weapons. The world's second-largest economy also boasts one of its largest nuclear industries with 55 reactors operating, 11 more planned, and a huge new reprocessing plant which will add to the 45 tonnes of plutonium already stored around the country.
In 2002 senior opposition figure Ichiro Ozawa spelled out the implications of goading this sleeping giant when he told China that it would be "a simple matter" for Japan to build "3,000 to 4,000 nuclear warheads" if its neighbour got "too inflated". Most experts believe a bomb could be built in six months.
In public at least, new prime minister Shinzo Abe resists such calls. In a Diet question-and-answer session this week he reiterated Japan's three nuclear principles: that it will not "manufacture or possess nuclear weapons or allow their introduction into" the country.
"I would like to clearly state that there will be no change to [ these principles]," he said.
But the reality of Japan's strict anti-nuclear stance has not always matched the politicians' rhetoric. Nuclear-armed US vessels have secretly docked in Japanese ports. In the 1970s prime minister Eisaku Sato commissioned a nuclear feasibility plan which was so politically explosive it stayed buried for 20 years.
In the near term, most experts believe Pyongyang's bomb is likely to push Tokyo closer into the arms of the US, under whose nuclear umbrella Japan has sheltered for half a century. Mr Abe has already pledged to speed up the development of an as yet unproven joint missile defence shield and to boost defence ties, a strategy that inevitably brings him into conflict with Japan's "pacifist" constitution.
But against a background of growing regional instability and the likelihood of further challenges from Japan's unpredictable neighbour, few of the A-bomb survivors are prepared to bet that the nuclear freeze will hold forever.
"There are no words to describe that happened to our city," says Mr Kuboi, who has watched in despair as the world's nuclear club has grown from one to eight in his lifetime.
"Our hopes have gone up and down since 1945, but I can't remember a time as bad as this."