Takeshi Bushijima

Under the hood and mask he keeps over his face is a boy who looks to be somewhere in his early to middle teens, with scruffy short hair, faint eyebrows, and soft features. Years of bottling his Quirk left a visible mark on him: the poison pooling in his body drained the color out of his skin and gave him a sickly cast. Once the buildup is finally vented, he looks like a healthy young man again.

Takeshi is gentle and thinks about other people first, which is exactly what makes his situation unbearable. He does envy Heroes their freedom to use their Quirks openly, but the feeling has no malice behind it; it comes from knowing that he must vent his own power somewhere or be destroyed by it, and that the law offers him nowhere to do it.

Above all else he refuses to put anyone in danger. That is why the poison sat inside him untouched for years, and why, on the rare occasion he has no alternative, he hunts for a place with as few people around as possible before letting go. His offense is really one of neglect, born of a conviction that the problem is his alone to shoulder. When Deku noticed he was unwell and offered help, Takeshi simply told him nothing was the matter.

Because using a Quirk to injure anyone is forbidden regardless of intent, Takeshi spent years bottling up Poison Gas rather than risk it, and the stored toxin steadily wrecked his health. He was in that state when he crossed paths with Mirko and the U.A. students working under her. Bumping into Izuku, he asked whether he was a hero, and on hearing that Izuku was a student doing hero work he made a bitter remark about how freely some people get to use their powers, then began coughing. He waved off Izuku's concern, told him to keep away, and hurried off.

With nothing left to hold, he fled into an empty alley and released everything, and the resulting cloud left several bystanders incapacitated. The news carried it, and Izuku recognized the hooded man from earlier. Mirko's group gave chase, Ochaco floating up to spot him running across town while he screamed at them to stay back. Katsuki read him instantly, seeing envy of people with useful Quirks in his face and guessing he was trying to let his own power out. Takeshi meanwhile kept moving, breaking off down a different path when he saw a crowd at the alley's far end.

When the Heroes cornered him and moved in, Deku stopped them. Asked why he was shielding a villain, Izuku answered that the boy meant no harm and had no control over the gas. Takeshi confirmed it, explaining that holding it in was destroying him but that anyone with a dangerous Quirk gets branded a villain under the system as it stands, and asked whether that made him one. Katsuki's answer was a plan. Mirko, who saw only a criminal, was talked around by the students' faith in him, and Deku's steady reassurance eventually persuaded Takeshi to trust them despite his fear of hurting the people nearby.

Uravity used Zero Gravity to lift Katsuki and Takeshi into the sky, where Takeshi emptied himself into the open air and Katsuki set the whole cloud alight with Explosion, scattering it in a burst of detonations overhead while Deku told him that saving people in trouble, not beating villains, is what the job actually is. Freed of it at last, Takeshi wept and threw his arms around Katsuki, who did not enjoy it. He was still arrested for the harm the gas had caused, but the truth reached the public through the news, and enough citizens sympathized to sign a petition asking for a lighter sentence.