Of all the poor decisions made by the Japanese in WWII, the most perplexing to me was their naval construction. They hit upon a very effective carrier design with Shokaku & Zuikaku. They were large, fast, had good aircraft capacity and were hard to kill. Even though they were not going to make 24 of them as we did with Essex class carriers, there is no reason they could not have built another six or eight on a production basis. There is no good reason to have stopped at two and gone the route of Taiho and Unryu.
So many bad decisions.... IMO the choice to not put self sealing fuel tanks and armor in the seat/cockpit in almost every naval aircraft was just plain stupid. Their Army planes were slightly better, but not by much.
Also no PT boats! They used modified LCP's (armed barges) for adhoc PT boats how retarded is that?