I have a feeling the Kaga model was melted down for the silver. Interesting to see the original design though - similar to seeing the original design for the Lexington class which was likewise converted to a carrier design.
I don't understand why anybody would destroy models - *maybe* confiscate, but just outright destroy? There weren't many IJN ships left after the war - those models would have been perfect to help preserve the history without posing any threat or costing a lot to maintain. It would have been even better if someone had the foresight to hire the model builders, who obviously had extensive knowledge of the IJN ships, to create some more examples of various ship classes for future museum collections. I suppose there was too much animosity and bigger problems to think about at the time... but at the very least they could've preserved what was already built.