As the student council look for someone to write a script for their play, Sayaka approaches Yuu, who had Koyomi in mind but didn't bring it up out of concern for Touko, and tells her to look into the student council president of seven years ago. Unable to find any relevant documents from seven years ago, Yuu learns from both Rei and one of the teachers that the president back then was Touko's older sister, Mio, who died in a traffic accident before she could perform at the culture festival...