S1·E6 Vice Penalty

After working with the Literature Club members to make a personalized video game for Jurai's birthday, Sayumi Takanashi, who has the power to revert things to their original state, catches a cold. Jurai pays Sayumi a visit at her house, where he meets her younger sister Maiya, though Sayumi attitude suddenly changes when Jurai bring up how she was the student council in middle school. The next day, after Jurai hears from Maiya about how Sayumi had originally wanted to join the student council during high school, Mirei theorizes she may have turned it down due to her powers. This leads Jurai to recall an incident that happened ten months ago in which Sayumi, who suggested they use her "Root of Origin" ability to remove everyone's powers, battled against Jurai who was against it. The result of that battle showed that Sayumi's power could not erase Jurai's Dark and Dark, as their powers were meant to be accepted as part of themselves.