Shinryaku Enban Kinokonga

Deep in the mountains of Japan, a flying saucer smashes into the earth. Fearful of the strange and hyper-intelligent beings they find inside, the government hides from the public all news of the alien craft. But it's not the aliens themselves that they should be afraid of-the real danger is the parasitic spores they brought with them! Will earth survive the UFO MUSHROOM INVASION?!

(Source: Living the Line)