Biiiig issue. The pacific theater of WWII ended in 1945. Their signature warplane, the Mitsubishi A6M "Zero" ceased to be operated after Japan surrendered in 1945. While it's true there were some holdouts, still fighting the lost war as late as 1974, they simply could not operate a Zero 8 years later. Lack of spare parts, fuel being good for about a year, and no doubt the US navy being attracted by reports of a still-hostile Japanese airfield would doom their ability to pilot any warplanes for more than a year at most.
Furthermore, the Imperial Navy (along with the rest of Japan's armed forces) were dissolved after their surrender in WWII.
Simply put, the pilot of the warplane could not have been dated to 1953 if he was a member of Japan's armed forces.
Fiurthermore, you fail to do anything truly interesting with the SCP. Most modern successful SCPs typically aren't just reports on objects, but stories in the form of reports on objects. A plague is boring- the story of a community trying to survive one is interesting. A sprite is boring- the story of some poor shmuck who weathers the daily mischeif of said sprite is interesting. Cthulhu is boring- the story of him trying to take a vacation at Pismo Beach without causing a mass panic is interesting.
So, what's the story here?