As usual, Eri's backstory is completely tragic due to suffering under Overhaul. When she is taken to the doctor after Shocker is defeated to make sure she is okay, she completely freaks out and refuses to leave Izuku's side. The worst part was when they took out a needle to take a blood sample, which causes Eri to repeat a Madness Mantra until it is put away. Even then it takes another 30 minutes for her to calm down and then another hour before she let the doctors even do simple things with her.