When you were a baby your parents sold you to Overhaul and he used you as a guinea pig for years until your 5th birthday. One day, while you are in your cell just returned from an experiment, through the glass you see Overhaul passing and stopping in front of the cell. He stops there and then the villain Tomura Shigaraki joins him. Overhaul: Since we now work together I would like to introduce you to one of my most important guinea pigs.. Shigaraki stands still with an unreadable expression