Black

Black, rendered in the dub as Dark, is the Transformation Quirk carried by Shihai Kuroiro of Class 1-B. It functions at contact range and enters the story in Chapter 198, arriving in the anime in Episode 93. Any sufficiently dark surface becomes both cover and a road for whoever holds it.

Anything dark-colored is a valid host. That covers objects whose color is natural and objects only darkened by circumstance, shadows included, and once merged the user moves through the darkness freely. Mass never factors in, so a cape or a mushroom is as viable a destination as anything far larger.

Items that already move on their own can be driven around while occupied. That quality gives the Quirk a specific edge over Dark Shadow, since Fumikage Tokoyami's dark-colored living appendage can be entered, seized, and made to act against his wishes. Tight, badly lit spaces suit the power best, because shadow is plentiful there and the walls themselves keep opponents from fighting or fleeing cleanly.

Light undoes all of it. Brighten a shaded location and the shadow covering an object disappears, ejecting the occupant on the spot, which leaves the Quirk badly exposed to light-based powers. There is also a gap while the user waits, ability primed, until something dark comes within reach. An opponent who grasps this can shove the wielder into a dark object they happen to be holding, trapping them there with no way to leave under their own power.

Shihai Kuroiro started out able to merge and nothing more. Training changed that, and he can now move the black objects he occupies, though only the ones that were mobile to begin with. In combat he uses the Quirk to duck attacks and set up ambushes, and once inside a black object he races through its entire structure at high speed, even while carrying another person.

Comparisons to Mimicry are natural, but the two diverge on several points. Black demands a particular color while Mimicry does not; Mimicry caps out at objects smaller than a refrigerator unless Trigger is involved, whereas Black shows no such ceiling. Joi Irinaka could reshape whatever Mimicry occupied at will, while Shihai needed to strengthen his own power first before managing anything comparable, and even now he is restricted to making mobile objects move. Black also shares Dark Shadow's profile of thriving in gloom and faltering under light. In the first School Briefs light novel, a young girl called Yuka manifests a comparable ability, fading into shadow and commanding whatever sits in the dark.