Take a deep breath. Repeat after me: 'Japan is not going to develop nuclear weapons.' Repeat. Feel better? Yes, North Korea's nuclear test is a blow to the regional security order. It is a bitter defeat for diplomacy. And yes, Japanese - and mainland Chinese, Americans, South Koreans and others - are concerned about its implications.
But the fear that Japan will develop its own nuclear weapons, as a consequence, is pure fantasy. Japanese understand that the nuclear option is a last-gasp, desperate move that would create more instability and insecurity than it would eliminate.
To be sure, North Korea's test complicates Japan's national security planning and compounds popular insecurities. It also provides fodder for conservatives and nationalists who demand a more robust defence posture. It will be cited by Prime Minister Shinzo Abe and others as they campaign to revise Japan's constitution.
Over a decade ago, Tsutomu Hata, who was prime minister, acknowledged that 'Japan has the capability to possess nuclear weapons'. But capabilities alone do not determine a country's security policy; intentions are even more important.
Japan still lacks the will to develop nuclear weapons - and for very good reasons. Perhaps most powerful is the resilience of the nuclear taboo in Japan. The experience of the second world war is still strong in the popular consciousness, and the Japanese public remains highly allergic to the thought of developing its own nuclear weapons capability.
Japanese security planners recognise that a national nuclear arsenal would be destabilising, and would actually diminish Japan's security. Building a Japanese bomb would further erode the global non-proliferation order, generate greater mistrust among neighbours and prompt allies to question its strategic intentions.