You might be right with China, how ever why should the UK flip China for Nippon. By the way Germany was better connected with China than the UK. As practical example was the equipment of the Chinese nationalist army.
Hm ... If Japan develops as in OTL and Germany continues to support China, it could develop into a nasty conflict.
In this TL, Japan is neutral during the Great War, but will continue to seek territorial expansion in the future. First of all in Manchuria. As in OTL, I expect the Anglo-Japanese Alliance to be terminated in 1923.