This Achievement requires a Chinese Warlord to conquer all Chinese and Japanese cores not including the states of Hong Kong(326) , Macau (729) and Guangzhouwan (728) which are controlled by the European Countries of United Kingdom, Portugal and France. This achevement is possible if the Warlord usurps China because it is based on tag rather than name of country and the tag stays the same when changed to China
Cooperation with the Nationalists
Follow the Cooperation With the Nationalists branch of the focus tree and make sure the warlord becomes China. This will make all Chinese divisions as the player's. By this time, Japan will be at war with the Chinese United Front. Defeating Japan will be similar to Awake and Angry, however this achievement calls for the annexation of Japan. Research Naval Invasion tech and submarines to do that.
Once Japan is pushed out of Asia, do not accept their white peace. Kick out the Communist Chinese and declare war against them or follow the Chinese focus tree to Anti-Communism. If this is not done, they will make a civil war against the Chinese United Front by stealing all of the land. Take the Subjugate the Warlords to puppet the warlords. Make sure all the warlords are puppeted as it is the best possible outcome for that focus. Decrease their autonomy to annex them. As for Japan, Naval invade when ready. If the Allies or Soviet have a large contribution, you can pre-empetively puppet Japan and annex it through the autonomy system. You get the achievements when Japan and all warlords are fully annexed.