Izuku manages to consistently use One for All at 100%, without breaking himself, half way through his second year. He graduates with that power tightly regulated, completely under his control; his quirk is his, completely. The graduated class 3A have a word for it when Izuku - Deku - goes 100%. It's a physical sensation, they learned early; a pressure in the air and on their lungs and down to their bones and blood. Everyone within his vicinity can feel it. They call it going green. And then, in a fight against the villain Jupiter, Deku goes green for the first time since UA. One third of the people at the scene collapse to their knees.