Stiffening

Shikkui Makabe of Ketsubutsu Academy carries this emitter Quirk, which requires contact to function. It first appears in Chapter 104 and is animated in Episode 54.

Two other powers frame it neatly. Hardening runs in the opposite direction by toughening only the user's own body, while Softening does the reverse job on foreign objects, making Stiffening the mirror image of both.

Anything Shikkui lays hands on can be made rigid. He works the process by kneading a target between both palms, and the transformation is dramatic: rubber balls treated this way take on the toughness of concrete and will shatter solid rock if thrown hard enough.

The limits are firm. Living beings are simply outside the Quirk's reach. Hardened objects also carry vulnerabilities of their own, offering no protection against acid and remaining liable to get stuck in viscous substances.

Shikkui Makabe is the sole holder. His most effective showing comes as a support role rather than a solo one.

Paired with Boomerang, the Quirk shines. Shikkui supplies reinforced projectiles for that ability's user to throw, turning ordinary objects into something with real destructive weight and making the two powers a natural combination.