I have mixed emotions about this (having lived as a military dependent in Japan for several years.)
Clearly, Japan is conflicted over the remaining (smaller than ever) US footprint, yet cannot defend itself as even South Korea is allowed to do (the Japanese constitution.)
I think China sees this as a dual opportunity, first to take a leading position in controlling their side of the Pacific and also to pay back the Japanese for the horrors of WW II.
The gains made by the western powers during WWII are in danger. China & Russia extending their influence, while the U.S., Europe, & Israel are threatened.
All due to American economic and foreign policies.