I also agree with SWJED on this one. You may gain some short-term bennies from China by doing this, but it certainly would send the wrong signal to other powers in the region. There are also, as cmetcalf82 pointed out, a number of existing issues with Japan and the rest of Southeast Asia that would need to be addressed before any real steps foward could occur. Both China and the Koreas have long-term issues with Japan. There needs to be clear thinking about policy in this part of the world, but abandoning longstanding treaty obligations for limited or undefined gains isn't a good way to start.