Yuuko Kirishima (桐島 有子, Kirishima Yuuko) is a student in the Seikyou Academy who has been missing from school for an indefinite time. Several rumors about her have spread across the campus, one of which is based on her first name which is read as "Yuuko", a fact that has earned her some unwanted attention by being linked to the school's ghost stories and thanks to that and her constant involvement with the Paranormal Investigation Club she probably is the most developed side character in the series.
She purposely becomes the inspiration of the ghost story "Yuuko-san is back".