Fissure (亀裂, Kiretsu) is the 22nd chapter of the Kiseijuu manga series, written and illustrated by Hitoshi Iwaaki.
While out with Murano, Shinichi becomes aggrivated and yells at her, after he's continuously asked about why he's changed. Yuko is told by her brother, about the existence of the parasites, in order to keep her safe. Though after following Hideo, she learns that he's one of these creatures. At school, she tries to talk him out of killing more people, but Hideo prepares to kill her instead.