S3·E5 This Mundane World

Yuzuki accidentally bumps into first-year student, Katase Ririka, causing her to break a beaker. The two of them report the damage to teacher Mio Niiyama, who lets the two off without punishment. The next day, Ririka's grandmother shows up at school and accuses Mio of picking on Ririka and continues to verbally attack her over the phone that night. The situation intensifies as Ririka's grandmother hands out leaflets that defame Mio and says she will keep Ririka home until Mio resigns. Mio tries to get Ririka to clear her name, but Ririka deliberately slanders Mio to her grandmother, meaning Ririka was the cause of her grandmother's drastic actions. Saddened, Mio sends Ririka to Hell.