In the event of WW3 it's going to involve either Russia or China, neither of whom Japan would even consider allowing to come to further dominance, even by inact

In the event of WW3 it's going to involve either Russia or China, neither of whom Japan would even consider allowing to come to further dominance, even by inaction. Japan would be at the White House Day 1 of the war offering their 100% backing including all steel production in both countries if needed.