I Know What You Found... Unfortunately not Japanese.
P-3 indexed.jpg 36.63KB
P-3 upside down.png 66.39KB
You have found the remains of a Lockheed P3A Orion that went into Subic Bay in 1971. Specifically the #1 or 4 Nacelle. No cockpit, no wheels. The wheels were in #2 and 3 nacelles.
See story here...including a picture of the salvaged remains- minus the nacelle you found!
Isn't the interweb wonderful!
From what I see, Subic offers wreckage exploration opportunities to last a lifetime. Best wishes and be careful out there.