Decay

Decay (崩壊) is a Quirk used by Tomura Shigaraki.

Description
Decay allows Tomura to destroy anything his hands touch, making it crumble to dust. Whether the target is organic or not, the Quirk will work without fail. The speed of the disintegration can vary from slowly to almost instantly.

Decay will only occur when all five fingers touch the target, indicating that the activation of the Quirk is not voluntary, or at least that Tomura has clumsy control over his own Quirk, avoiding using all his fingers to touch objects as a safeguard. As such, Tomura is often careful with his hands when touching objects he doesn't want to destroy.

Because the Quirk requires all five fingers to touch an object in order to be activated, it's possible to counter Decay through Quirks that allow one to manipulate fluids or particles, which Tomura can't properly touch with all his fingers.