Yeah the Japanese navy sunk all of the major US capital ship save the Enterprise and Ranger. US production rebuilt the fleet and then some. Japan just could not compete.
Plus the fact that the IJ forces were not rotated out of combat zones. This created a great attrition espically of the pilots. I.m sure the JSDF has abandoned these policies.
As to the amphib excersises in San Diego..I wonder if this is just a pre-cursor to a larger excersise for them nearer to home?.Perhaps a larger landing say 2000 troops at Okinawa. I'm sure that would raise some eyebrows in the PRC as well as the rest of Asia. 'Cause you ain't got 4 of these for nuthin'.