Post Midway, the biggest problem faced by the IJN wasn't replacing their lost carriers, being as they still outnumbered us carrier wise... It was the loss the airgroup personnel from their two best trained, and most experienced carrier divisions... That hurt them the most... They had all their eggs in one basket, and they lost it all in one fell swoop... The ones that were left, were frittered away in the Solomons.. (instead of using their experience to train the next crop of aircrew, as the USN did) They replaced the carriers in time for the Mariana Ops, but the aircrews were green as hell, and they lost that whole group too, LOL!!! After that, there was really nothing left... Except their surface fleet, which was very potent, but poorly commanded...
RC