Decay

Tomura Shigaraki's touch, which turns things to dust.

Decay is the Quirk of Tomura Shigaraki, the main antagonist of My Hero Academia. It disintegrates whatever he touches with his fingers. After it evolves, the decay also spreads to anything connected to the thing he touched.

Lore & Background

The Quirk first shows itself when Shigaraki is a child called Tenko Shimura. It kills his family one by one, his mother even as she tries to comfort him, and in his rage he turns it on his father on purpose. All For One later says that the boy's locked-away memories were holding Decay back from its true power. Late in the story All For One's vestige claims he secretly gave Tenko the Quirk in the first place.

Reader's Guide

In the battle of Deika City against the Meta Liberation Army, Shigaraki decays the base of a tower and his Quirk evolves, so that it destroys whatever is connected to what he touches. When he wakes during the raid on Jaku Hospital he amplifies Decay with All For One's Quirk, killing many heroes and destroying the hospital and much of the surrounding city. He also kills the American hero Star and Stripe with it. The heroes' cage for him in the final war is built with structures that react to Decay, and Monoma keeps a copied Erasure trained on him.