Brainwashing

Brainwashing, written in Japanese as Sennō, is the Quirk held by Hitoshi Shinso. It is an Emitter type whose reach extends as far as the user's voice carries, making it one of the stranger powers in a series that mostly deals in fire, force, and mutation. The ability entered the manga in Chapter 33 and the anime in Episode 20, both during the U.A. Sports Festival.

Hitoshi himself spent years resenting it. Because the power could not touch the Villain Bots used in U.A.'s practical entrance exam, he had almost no path into the hero course by the normal route, and people around him tended to read the ability as something a villain would carry. That impression flipped once the Sports Festival put it on display; watching it work, plenty of Pro Heroes wished it were theirs and criticized U.A. for nearly letting that potential slip away.

The Quirk drops a target into total obedience, where every order from the user gets carried out. Getting there requires one thing: the target has to answer something the user says out loud. Activation is deliberate, so Hitoshi can hold an ordinary conversation without seizing control of anyone. He can keep several people under his thumb at once but can only claim them one at a time, and focus on the intended victim is part of the requirement.

Being caught is described as a fog settling over the mind. Victims stay broadly aware of what has happened even as their eyes go milky and their expressions empty out, leaving them trapped inside bodies moving without their consent. Until an order arrives they simply stand still and wait. Training for his transfer into the hero course pushed the ceiling higher: he can now make a controlled person speak, and forcing speech this way strips emotion from the words, letting a victim slip past lie detectors or Quirks doing similar work.

The weaknesses are many. Complex mental tasks are off the table without further training, so nobody under his control can write out information from memory; commands have to stay simple. Silence is a complete defense, since without a verbal response there is nothing to hook into. A hard enough jolt or comparable pain snaps the hold, which is how Mashirao Ojiro came back to himself after his shoulder took a knock in the Cavalry Battle. Non-living things appear immune, explaining the entrance exam failure. Voices routed through electronics lose their grip, since the device converts the sound into an electrical signal. Control also stops at behavior and never reaches thought or feeling, a gap Izuku Midoriya exploited using One For All to break free. Blinding light shatters the effect too, as All For One demonstrated when he severed Hitoshi's hold on Gigantomachia.

Hitoshi Shinso is the Quirk's only user. He carries no offensive or defensive capacity whatsoever, and the power still finishes fights, because a captured opponent can simply be instructed to lose. During the Sports Festival final he told Izuku to turn and walk out of the ring, and left unattended, a victim just stands motionless, which hands Hitoshi a free opening to strike or restrain.

Surprise is the whole game. He opens with idle conversation and takes hold the instant someone replies, and an opponent who already knows the trigger can still be baited into speaking through taunts or misdirection. The ability doubles as support: he steered a group of students into carrying him across the ice when Shoto Todoroki froze the Obstacle Race course, and he assembled his entire Cavalry Battle team by taking control of three hero students. Size is no obstacle either, as proven when he claimed Gigantomachia during the Final War and rode the behemoth into the fight against All For One. Support gear rounded out the kit before the Joint Training Battle: his Artificial Vocal Cords, worn like a mask, reshape his vocal tone without electronics, enabling the Persona Chords Ultimate Move. Mimicking another person's voice, he coaxes a reply out of someone who would otherwise never give him one, and Ibara Shiozaki fell for exactly that trick.

His confirmed victims span the whole story: unnamed Obstacle Race students, Mashirao Ojiro, Yuga Aoyama, Nirengeki Shoda, and Tetsutetsu Tetsutetsu in the Cavalry Battle, Izuku Midoriya twice over, Jurota Shishida and Ibara Shiozaki in Joint Training, Yuga's parents, the Sludge Villain, and Gigantomachia.