I hate to rain on everyone's parade, but Japan shouldn't be so readily taken in by Chinese Premier Wen Jiabao's recent speech in the Diet. This is because China, despite the flowery good language forwarded by Wen, is still a totalitarian regime willing to interfere in another country's domestic politics.
In Japan's case, the interference is with the right of people to worship and pray wherever they want whenever they want, such as at Yasukuni Shrine. The true test of whether a country is earnest in developing peaceful ties will always depend on whether it can desist from interfering in the domestic politics of another -- not undermine it. It will also depend on China resisting the temptation to seek legitimacy by emphasizing the history of another country while denying its own, namely the death of millions of Chinese under communist rule.
Pushing the premise that Japan wronged China by murdering millions while China murdered millions more is disingenuous to say the least -- that is unless Chinese killing Chinese is preferable to Japanese killing Chinese.
Perhaps that frame of thought is acceptable to the regime in Beijing, but I doubt that the countless souls who perished under a murderous Chinese government would agree. And I doubt whether they would encourage any nation to drop their guard against a regime that continues to deny events in its own sordid past.