As the Obama administration grapples with North Korea, U.S. officials are investing considerable hope in securing Chinese cooperation. If that support fails to materialize — while Beijing continues to display unhelpful assertiveness on issues such as cyberspace and the South China Sea — concerns are likely to deepen in Washington about the kind of great power China is proving to be.

Here in Tokyo, such worries about China are already well-entrenched — and provoking as much anxiety as are developments on the Korean Peninsula. But they are also the source of something paradoxically hopeful: an impetus, albeit still tentative, for reform and renewal.

In the past two decades, Japan has become all too synonymous with decline, hobbled by anemic growth, dysfunctional politics and death-spiral demographics.