Two months after the Scorched Halloween incident, Tatsuya and his friends hold a going-away party for Shizuku who will be studying abroad in America. With the start of the new semester, an exchange student from America arrives at First High School.

A string of bizarre murders occurred where the victims were found to have most of the blood drawn from their bodies. Due to the methods used by the killer, they were called "vampire incidents," and similar incidents were also occurring in America.

A parasite is an information body that was generated from the spirit dimension. How could an entity from another dimension appear in the physical world? An evil visitor of unknown origin infiltrates its way into First High School.