Afterschool Quicksilver (放課後のクイックシルバー, Houkago no Kuikkushiruba) is a ghost story which tells about a vengeful spirit that is infamous for destroying classrooms in Seikyou Academy.
The story of the Afterschool Quicksilver tells about a girl who died from mercury poisoning in a chemistry class accident. After her death, her spirits lives on inside the school grounds as a quicksilver, a spirit which becomes a poltergeist, a paranormal entity that is famous for throwing inanimate objects where it manifests. Rumors about the Afterschool Quicksilver originated from an incident in which a girl, later identified as Haruka Yoshizawa, was seen in the middle of Seikyou Academy's thrashed chemistry laboratory, although the rumors of quicksilvers existed before the aforementioned incident.
Teiichi Niiya of Seikyou Academy's Paranormal Investigation Club first hears of the story of the Afterschool Quicksilver from his classmate Yuuto, who reveals the story as a spreading rumor throughout the school, and agrees to look into the possible case.
Later that day, Teiichi is accompanied by Yuuko Kanoe and Momoe Okonogi while doing their cleaning tasks at the end of class when he barely avoids a desk that fell from their classroom. Teiichi later finds out that their classroom is a chaotic mess with most of the school equipment destroyed; in the middle of this is an unconscious girl, who Teiichi discovers is Haruka Yoshizawa, his and Yuuto's classmate.
The events that happened in the room of Class 1-C caused the faculty to decide on moving the class to a new classroom.
- The term "quicksilver" is originally used as an archaic name for the element mercury.