Transformation

Transformation (変形 Henkei)-type quirks are abilities that cause the user to take on a temporary alteration of some kind. Transformation-type quirks allow the user to temporarily "transform" their body in a variety of manners, sometimes enhancing existing features, removing features, or adding new features to the body altogether. They are the third most common type of quirk, after Emitter and Mutation but more common than Psi types, though many researchers suggest that Psi is actually more common, just less often registered as Psi instead quirklessness or Emitter.

Transformation-type quirks usually require a close-range proximity in order to fully utilize them in combat due to them only affecting the user's body. While Transformation-type quirks are often quite powerful, their biggest weakness is that their effects are often temporary, and over-exertion usually leads to negative repercussions on the user's behalf. Transformation quirks can also be limited based on the user, how resilient their body is, and the resources they have available to them (Ex. Tetsutetsu Tetsutetsu describes that his Steel quirk softens if he doesn't consume enough iron, and suffers from iron fatigue if he maintains it for too long). Some users condition their body in certain ways so that their quirks can operate more effectively.

Transformation-type quirks are the only known type of quirk that can bestow the user attributes they do not normally exhibit by default. Because this type of quirk combines the activation time and mutant-shape aspects of the other quirk types, it is also often known as Hybrid or Composite. Some researchers suggest that Transformation is actually a subtype of Mutation type quirks, similar to how Accumulation quirks are a subtype of Emitter quirks despite have transformation-like qualities.

Transformation-type quirks generally affect the user exclusively, the only known exceptions being Seiji Shishikura's Meatball.