In 2010–12, Sino-Japanese relations deteriorated without the Yasukuni Shrine or Chinese human rights violations in the forefront. To improve relations, attention should turn to what I label the ideological, sectoral, and horizontal dimensions of a national identity gap between these countries. They have each figured in the decline and offer more promise than the temporal dimension, with its symbols of wartime memories, and the vertical dimension, where sensitive Chinese internal affairs are at stake. The sectoral dimension comprises political, economic, and also cultural national identity, each of which has grown more intense in China, while cultural identity is still a force in Japan. Establishing an East Asian community is now the centerpiece in the hope that the horizontal dimension will be an impetus for mutual understanding, yet the notion of community is repeated with no sign of a shared vision of the outside world, whether the US role or the international arena and regionalism. With South Korea, their partner in trilateralism and North Korea's transformation at the crux of all three of these dimensions, this paper emphasizes the way divergent views of the peninsula keep growing in importance for bilateral relations. It suggests ways to reframe relations through cooperation over Korea. As difficult as Korean relations are for both states, it is a test case for their identity gap.