Kujo Rina is a chemistry teacher and the homeroom teacher for the 3rd grade D class at Horai High School. She doesn't have a connection with her students. On the school's graduation day, Kujo Rina is pushed from the 4th floor and falls down. She catches a glimpse of a school uniform sleeve on the person who pushed her. At that moment, she wonders why she was pushed and that she does not want to die.
