Set 128 years after Izuku "Deku" Midoriya's time, the world has changed significantly. A chaotic time known as the Singularity Collapse led to the fall of traditional hero schools like U. A. Now, there is Eternal Academia High, a global institution managed by the Core Authority Council.
This new system enforces a strict genetic caste based on quirk lineage and aims to create obedient "Preservers of Order" instead of true heroes. Underneath this controlled society lies the Underscape, a grim underground area where the forgotten, mutated, and unregistered Nullborns live.
In the Underscape, Kaizen Ryou, also known as K-0, struggles to survive and thought to be quirkless, he actually possesses a rare ability called "Prime Evolution," which allows him to adapt to life-threatening situations. While physically damaged, Kaizen tries to hide his powers and feels increasingly isolated from humanity.
Meanwhile, at Eternal Academia, Aira Midoriya, a descendant of Deku, faces the pressure of her family legacy. Known for her potential, Aira resists the academy’s control and seeks true heroism, contrasting sharply with Kaizen's dark experiences.