Residents of a small town become obsessed with spiral shapes. How is that a movie? Well it's Japanese. Give it a smoke if Tetsuo the Iron Man and House are just a little too weird for you. Maybe look at spirals for a while first.
There is something compelling about spirals isn't there? Remember the old Twilight Zone opening, and how it made you feel sort of psychologically dizzy? And you liked it? And wouldn't stripey socks be better if they spiraled up? And don't you sometimes want to fall into a whirlpool or get sucked up by a tornado, and see where you go?
I'm not sure this should be a movie though. I mean I'm glad it is and they pulled off some beautiful gore scenes, but not as beautiful as the amazing artwork of Junji Ito. I think the movie does about as well as it can in presenting a vibe so endemic to his distinctive artistic style. It's suitably surreal and suggestive of Ito's work, but for the full trip you'd have to see the manga.
I don't know what it's about or how spirals can curse a town. That's one reason I dig this kind of story - the hint that everything is relative. There are infinite realities other than the one created by human consciousness. There's an angle from which this story makes perfect sense, and while we can't see from that angle we can know it's there and feel that tugging on the brain of something just outside our field of view.
That's not to say any made up crap is automatically interesting. I wouldn't watch a movie about a town cursed by squares or air quotes. The trick is to pick something that already has a loose string you can unravel. I most certainly would watch a movie about a school driven mad by mind blasting revelations hidden within the multiplication table of a Pee Chee folder.