Acid

Acid, written 酸 and read San, belongs to Mina Ashido of Class 1-A. It falls under the Emitter category with a medium effective range, and it debuts in Chapter 11 of the manga and Episode 8 of the anime.

The power hands her corrosive liquid produced by her own skin, and it comes with a natural resistance to what she makes. Her coloring is part of the package, since the Quirk tints her skin a purple-pink, though the fluid itself reads as grey. How her horns grow has also been implied to track with how the Quirk develops.

Volume is no obstacle. Mina can push acid out of any part of her skin in quantity and steer it once it is loose, within limits. Potency runs high enough to eat through solid material, metal included, which puts anyone leaning on destructible gear at a disadvantage, the belt and cape worn by Yuga Aoyama being the standing example.

Two properties are hers to adjust. Turning solubility down keeps the fluid from becoming lethal to most living things. Turning viscosity up yields something thick and slimy that clings where she puts it and works as a barrier. She also borrowed a trick from Katsuki Bakugo and Shoto Todoroki, both of whom were taught by Endeavor to compress a Quirk before turning it loose, and applied that compression to her own output. At Maximum Output the result chewed through even Gigantomachia, whose durability is famous.

The bill lands on her body. Her tolerance is not permanent within a fight: the longer she produces, the more her skin surrenders its protection against what she is making. Push far enough and the Quirk turns genuinely dangerous to her, corroding her badly and draining her fluids to the point of severe dehydration. Training addressed some of this, since she generated acid constantly to toughen her skin against her own corrosion. She is still short of full mastery where human opponents are concerned and works more comfortably against inorganic ones, and slips have dissolved her own clothing, which is why her costume is built to resist it.

Mina Ashido is the only known wielder. Away from a straight fight, the Quirk serves as mobility and access: she burns openings into surfaces to get into guarded places, melts handholds into walls to climb, and slicks the ground so she can skate across it. Her footwear is acid-proof and perforated at the sole so her feet can secrete freely.

Her named techniques build on the same two dials. Acid Veil drives solubility and viscosity to their peak to raise a wall that stops incoming projectiles, hardened balls tougher than concrete among them. Acid Shot rains bullet-shaped droplets from her hands onto a target and the ground around them. Acid Layback dissolves the surface beneath her shoes so she can spin freely, and the momentum she builds lets her hurl objects with enormously increased force. That move pairs with Minoru Mineta in the Grape-Pinky Combo Mineta Bounce, first shown during the Joint Training Battle's fifth match: Minoru lays Pop Off spheres across the ground and walls, Mina spins and flings him, and he ricochets from one to the next.

Thicker applications go further. Acidman coats her entirely in high-viscosity acid that takes a rough humanoid shape, finished with a circular black outline and a pair of cartoonish white eyes, and anything striking her dissolves against it. Alma takes acidity to its maximum and throws that Acidman shell at an opponent outright. The Quirk even has a signature sound effect, "SHZZ", and its color differs between formats: grey in the anime, purple in the manga.