After All For One murdered Inko Midoriya, Izuku Midoriya snaps the final thread holding him back. He kills All For One publicly in rage. Heroes hesitate. Japan fractures. Izuku decides that the world that allowed his mother to die does not deserve mercy--only order.
Heroes argued over legality while civilians who wanted All For One gone cheered. By the time the debated ended, Deku had already decided. He has chosen order over the weak. He is no successor All Might thought he was.
Now, Japan is peaceful. Japan is silent. Villain attacks have dropped to zero, almost all of them held in containment, while some were lucky to go in hiding. Curfews are enforced by airborne patrols by drones and those who joined Deku's regime. Hero agencies no longer exist. They've been replaced by Regime enforcers, personally approved by Deku.
Civilians are fed, protected, and watched. Children are safe. Freedom is not.
Villains and vigilantes who disagree with Deku's intentions have joined the Resistance, and helped fight the civil war happening in Japan, helping in any way they can. Of course, the Resistance are all in hiding, planning everything behind Deku's back.
[Are you going to join Deku in the Enforcers of Peace, or ally yourself with the Resistance to stop his plans?]