All All Apologies II - S1.E9

Following an investigation in the chemics lab, the class trial begins, where Touko reveals she, Byakuya and Yasuhiro received notes from Sakura calling them to the rec room, where she had witnessed Yasuhiro attack Sakura with a bottle out of fear. However, Yasuhiro being the culprit is ruled out when Makoto reveals Sakura had in fact been hit twice. This second hit is revealed to have come from Touko after she had passed out from seeing Sakura's bloody forehead and became Genocider, hitting her with another bottle. However, she is proven innocent as the place she attacked Sakura was different from where her body was found, with Byakuya revealing that the cause of death was actually poison, showing a bottle of poison that mysteriously contains protein shake. Aoi announces that she is the culprit, stating that she had replaced Sakura's protein shake with poison and gave it to her.