What did the Japanese do with downed aircraft?

I know a lot of aircraft that crashed on land would be searched for intelligence. But, what if it crashed into a bay area or a lake would the Japanese try to recover it? Make dives down to it for intelligence gathering? I propose this question because now I know everything I am going to know about the crew of a crashed B-29 in Osaka bay but what would of happened to the plane? Is it possible that it's still there? Did the Japanese govt. keep any log of recovered aircraft of the enemy? I know in Europe the German airforce seem to put them back into service or at least learn more about them. Did the Japanese do the same?

 

In most cases in WW2 downed aircraft would be first examined to see if they were carrying any new equipment, and after that broken up for scrap. Any aircraft that crashed in the sea or lakes where it would be uneconomical to recover the wreckage for scrap would be left to rot.