If you eat matango, you become inhuman.
In the history of strange Japanese films, you would have to search far and wide to find one that could top Ishiro Honda's 1963 film Matango, which was known as Attack of the Mushroom People when it was first shown in the States. One of the more notable things about it is while the mushroom people don't actually start attacking in earnest until the movie is nearly over, it manages to hold the viewer's attention by slowly building tension and maintaining a sense of realism, both in its treatment of the situation and the characters who find themselves in it. Put simply, this is the most serious-minded film about people turning into mushrooms you will ever see and that may be the strangest thing about it.
As the film opens, we are introduced to a group of passengers that has charted the luxury yacht of a millionaire (Yoshio Tsuchiya) for a pleasure cruise. They include a writer (Hiroshi Tachikawa), a famous singer (Kumi Mizuno), a college professor (Akira Kubo) and a clerk (Miki Yashiro), with the ship's skipper (Hiroshi Koizumi) and a sailor (Kenji Sahara) along to assure smooth sailing. That isn't in the cards, though, for soon enough the yacht is wrecked in a violent storm and the passengers find themselves adrift in heavy fog, cut off from the outside world until they land on what they think is an uninhabited island. There they find that food is scarce (although there are plenty of mushrooms) and it isn't long before nerves are frayed and people start turning on each other -- that is until some of them turn to the mushrooms out of desperation and start turning into them.
Because Honda waits so long to reveal the fully-transformed mushroom people, he and his writers have to find other ways to clue the characters in to the fantastic danger they're in. One way is to have them tour a derelict ship where pretty much every flat surface is mottled with different colored mold. Then, after they take up residence in the ship, they are menaced one night by a kind of transitional human-mushroom hybrid, which turns out to merely be a delusion brought on by hunger and exhaustion. The creepiest image in the film, though, is reserved for the viewer alone. It's a simple shot of a crop of mushroom growing to enormous size before our eyes. When the same shot comes back later, only this time overlaid with some unnervingly childlike giggling, it's safe to say one is fully prepared for the madness to come.