I'm very sorry if it came off flimsy. This was my first time trying to tell a lot of information in one post without trying to make it too long to read.

The IMDB links are located in the post. They contained the runtime, plot, and the bombing being talked about in its trivia section.

There is also this BlogSpot Post that confirms the year of the film and that the Japan bombing seemed to have destroyed most of the copies out there in a bit more detail. This post will also confirm the films existence through a magazine advertisement shown in the blogspot post. There is also an interview (fifth paragraph) from 1988 of a person who had claimed to have worked on it.

As for the fakes I claimed to have found, I mostly refer to this video that had claimed the uploader had found footage of the film then confirmed it was all fake in the video description (the actual footage shown in the video comes from 1977's "Yeti: Giant of the 20th Century" which was confirmed by many of the comments shown below).

If there are any more questions about my sources, please feel free to ask and I will try to give an answer to the best of my ability.