In chapter #419 of My Hero Academia, the origins of Shigaraki's Decay quirk are revealed, showing that it was given to him by All For One as part of a plan to steal One For All. Shigaraki originally had a different quirk from his parents that All For One took away when he was a child. The chapter also confirms that the mysterious man who took young Tenko home was indeed All For One, who engineered the deaths of the Shimura family to groom Shigaraki as his pawn. The revelation of Shigaraki's tragic backstory adds depth to his character, showing how he could have turned out differently if he had kept his original quirk. As the battle against All For One continues, the direction of the story remains uncertain. My Hero Academia follows Deku, a hero-in-training at UA who inherits the powerful "One-For-All" quirk, as he learns what it takes to be a hero.