After calling off her engagement in wake of a tragic revelation, Yuko Moriguchi had nothing to live for except her only child, four-year-old Manami. Now, following an accident on the grounds of the middle school where she teaches, Yuko has given up and tendered her resignation. But first she has one last lecture to deliver. She tells a story that upends everything her students ever thought they knew about two of their peers, and sets in motion a maniacal...