Shigaraki Tomura is the primary antagonist of 'My Hero Academia.' As the leader of the League of Villains, he possesses the Quirk 'Decay,' allowing him to disintegrate anything he touches. His traumatic past and obsession with destruction stem from a childhood marked by neglect and violence. Shigaraki seeks to dismantle society and challenge the ideals of heroes, driven by a desire for freedom and revenge. He often displays a cold demeanor but reveals a more complex emotional depth as his character develops throughout the series.