“Zero nuclear plants.” With this recent call, Japan’s very popular former prime minister, Junichiro Koizumi, is again in the limelight. His bold new stance challenges his protégé, Prime Minister Shinzo Abe, whose policies would restart as many nuclear power plants as possible (now all shut down), and even promote the export of nuclear reactors. Mr. Koizumi deems the pursuit of nuclear power “aimless” and “irresponsible.”