I have a book that’s no longer published on this called The Niihau Incident by Allan Beekman. Included in it was that our intrepid pilot was escorted by another Zero on the way to Niihau. Both planes were shot up badly and the other pilot saw he couldn’t reach the island. He may or may not have been wounded as well. Anyway the other pilot gave Nishikaichi a salute and dove his plane into the water killing himself. I seriously doubt that he thought his plane would be found if he crash landed in the ocean but we will never know for sure.