Koro-sensei, Nagisa, and Kaede help to tidy up the storage shed, reminiscing over the past year together. Just then, Kaede suddenly attacks Koro-sensei with tentacles of her own, revealing her true identity to be Akari Yukimura, the younger sister of E Class' previous teacher, Aguri Yukimura. Believing Koro-sensei to be responsible for her sister's death, Kaede stole some tentacle serum from her sister's lab and arranged to join E-Class in order to exact her revenge, withstanding the pain of the tentacles while waiting for the right moment. As Kaede puts her own life at risk to battle against Koro-sensei with the full strength of her tentacles, Koro-sensei hears her inner voice, wishing to be saved.