Uzumaki

Uzumaki (うずまき, lit. Spiral) is a horror manga written and Illustrated by Junji Ito.

Plot
The story concerns the inhabitants of the small Japanese town of Kurôzu-cho that seems to be cursed by supernatural events surrounding spirals. Many people become obsessed or paranoid about spiral shapes, which starts resulting in several gruesome, realistically depicted deaths. Eventually people start transforming into something other than human, such as snails and twisted forms. In the end the town is cut off from the rest of the world, which leads to apocalyptic events and a revelation about the secret hidden under the lake in the middle of the town.