The story line is quite simple: a '60s version of the TV serie Lost. Just this time the crew is all Japanese and the arrive on the deserted island on a boat and not on a airplane! The island is apparently deserted, though the castaways soon discover a beached research ship on the other side of the island. An examination of the ship, the insides of which are encrusted with a thick mold, soon reveals that it had an international crew which appear to be involved in radiation and fallout research.
The fan of Lost will agree that this sounds quite known! Well, in the Japanese version there are black smoke but another danger is coming!
Animals are quite afraid of the islands, making it pretty difficult for the survivors to provide food. Mushrooms are on the contrary plentiful on the island; however the ship's captain warns the passengers not to eat them because of the danger of poisoning. A small supply of canned food is found on the research ship, but this only buys the crew some time. Inevitably, members of the crew begin eating the mushrooms.
And here comes the best bit! The crew of the abandoned ship hadn't vanished as completely as they'd originally thought.... The Mushroom People are coming to get you!
Here the original movie trailers from 1963.