Books like Uzumaki: Spiral into Horror, Vol. 2.

A sleepy town on the coast of Japan is under quiet, deadly siege, not by a person or group but by a primeval spiral shape whose victims include both parents of Shuichi Saito. In this second volume of the saga, Shuichi's girlfriend Kirie becomes further involved in the town's terrible secret when schoolmates start turning up as horrible human snails and something unspeakable is discovered within the walls of the local hospital.