I've been looking forever for this. As the title might suggest (Momotaro's Divine Sea Warriors) this, the first full length animated Japanese film, was a propaganda cartoon comissioned by the Navy to spread morale among youngsters. It was premiered just weeks before the surrender (which just shows its effectiveness) and was forgotten and for some reason neglected for years after the defeat. A copy was found in an old warehouse 1983 and a video was released in 1984. Whoever owns the copyright has shown understandable hesitation to distribute it in the West, or for that matter in other Asian countries.
From what I gather from the Anime encyclopedia, which is the source of the above facts by the way, the film starts out with several animals (a monkey, a rabbit, etc) training for the Navy when on graduation the monkeys younger brother loses his siblings cap and it falls into a river, and all the animals jump down into the river to retrieve it. Then we are inexplicably transported to a Pacific Island, where another group of animals is teaching the native youngsters how to play Japanese games (good sense of Imperialism here) but soon an airplane arrives caryring Momotaro, a traditional Japanese folk hero, with his traditional allies, our friends from the Navy academy. Most of them join naval infantry, but the rabbit becomes a pilot.
The movie gets blatent when a British memo is intercepted and the little band of (probably) cute animals and fairy tale characters drive the Brits out of the island. In the final sequence we see the "divine warrior" back in Japan celebrating their victory, then playing parachute over a map of the US.
It's 64 min. which is pretty typical for a first animation feature, and would be of great historical interest, not only to disgruntle Pokemon fans, but also a superb example of self-delusion & propaganda. And I'm sure it would have it's own surreal qualities.