Instead, the townspeople freely admit that they created the pictures by planting a darker-colored variety of rice alongside the traditional green rice. What they don't freely admit is that the whole thing is probably a publicity stunt, but at least it's not too tacky.
And I'm guessing that the rice harvested from this "tambo art" ("rice field art") is bagged and sold at a premium.
Finally, some comments on the linked-to Pink Tentacle page raise accusation of Photoshopping, but at its official website and blog, Inakadate officials freely admit to being instigators of the whole phenomenon.
The work of alien beings? No, it's the work of the mayor's office.