Good answer above, and to add an imperial perspective, Japan used increasing western involvement in the region to fan the flames of nationalist sentiment. Support among the population for Japan's expansionist ambitions in the region was in part a result of this anti-western theme.
In China, anti-Western sentiment contributed to a growing communist rebellion starting in the mid-1920s, and lingering resentment about the European empires' role in exploiting China helped spur that movement and others.
China and Japan reacted in very different ways to Western involvement in their region. China tried to stay the way it was. It thought that it could just keep going the way it always had because it had always been so powerful.
On the other hand, Japan reacted by trying to become much like the West. The Meiji Restoration totally changed Japan's government and society to make it more western.
By doing this, Japan was able to become a major world power very quickly, while China is just now getting to that status.
Both China and Japan had faced similar challenges from the West (both faced severe challenges from Western imperial powers and ended up signing unequal treaties with the West, with the new foreign presence instilling new waves of domestic turbulence) but had responded in very different ways. The elites of both countries responded to the challenges posed by Western penetration by initiating reforms. In Japan, the Meiji regime chose to remake themselves entirely through Westernisation, while in China, the Qing government chose instead to hold on to traditional Chinese values and institutions. China’s efforts at reforms, including the Self-Strengthening Movements and the Tongzhi Restoration, were in essential traditional answers to traditional problems. There was no significant, large-scale industrialisation in China and the Machus displayed little willingness to abandon traditional imperial institutions that were incapable to dealing with contemporary problems. Chinese cultural pride was just too deeply ingrained, so much so that it became an impediment, blinding many Chinese and preventing them from recognising the need to learn from the barbarians and for fundamental change. On the other hand, Japanese efforts to adopt foreign technology to meet their military and industrial needs were largely successful. The Meiji regime, however, saw that military technology and industrialisation could not be separated from institutional structures that had produced and accompanied such developments in the West, and showed little hesitation in transforming or abolishing traditional institutions in favour of those that could give Japan the modernity it needed to survive. Overall, the Meiji Restoration was a tremendous success for the Japanese and allowed them to join the ranks of Western new imperial powers.