The Oct. 22 general election is an ideal opportunity to debate major threats to Japan: Kim Jong Un's missiles, Donald Trump's Twitter storms, relations with China and whether three arrows or 12 zeros are key to gross national happiness.

But neither Prime Minister Shinzo Abe's arrows nor Yuriko Koike's zeros answer Japan's most difficult threat: demographic devolution. The platforms of Abe's Liberal Democratic Party and Koike's Kibo no To (Party of Hope) have this in common: no chance of altering a population-and-borrowing trajectory that will push the debt burden toward three times the size of the economy.

Yes, I know. Warning about Japan's aging and shrinking population veers toward Chicken Little territory. But the latest report from the International Institute for Strategic Studies (IISS) is sobering. The global think tank on political and military conflict sees a "looming crisis" that "threatens U.S. power and Asia-Pacific regional stability" in the likely loss by 2060 of 30 percent of Japan's population.