My Hero Academia: Heroes Rising

Nine needs Katsuma's Quirk because it possesses healing properties that can cure his terminal illness. The disease worsened as a side effect of the modifications Nine underwent to gain multiple Quirks. Nine specifically required a Cell Activation Quirk to survive, and Katsuma's Quirk matched the blood type compatibility needed for the cure.

Earlier in the film, Nine's gang attacks Katsuma's father and takes his Quirk, hinting that the villain was searching for the right blood type match.

Izuku transfers One For All to Bakugo during the final battle because they are overwhelmed by Nine's immense power. With Nine threatening to destroy the island and disable all the students, Izuku sees no other option but to temporarily give Bakugo the full power of One For All to maximize their counterattack against the villain.

The film builds tension as Nine consumes Quirk-enhancing fluids, pushing the heroes further into desperation.

The transfer appears to complete temporarily, but One For All remains with Izuku. All Might explains afterward that the previous wielders of One For All would want Izuku to keep it. The transfer was interrupted or reverted, leaving Izuku as the true successor.

During the battle, there's a moment where it seems One For All fades from Izuku entirely, creating genuine uncertainty about the outcome.

Shigaraki kills Nine out of spite after Nine is defeated by Class 1-A. Nine was a rival villain with powerful Quirks, and Shigaraki eliminates him to remove competition and assert his own dominance in the villain underworld. He vows to finish what Nine failed to accomplish.

Nine's ambition to rule a world with strong Quirks directly competes with Shigaraki's own goals, setting up the power struggle.

Nine possesses Weather Manipulation as his original Quirk, but Daruma Ujiko equipped him with a copy of All For One's Quirk, granting him access to eight additional Quirks. This allows Nine to use multiple powers simultaneously, overwhelming opponents with a flood of different abilities.

The film establishes early that Nine is extraordinarily powerful, having absorbed multiple Quirks from Ujiko's experiments.

Endeavor destroys the truck to stop the League of Villains from escaping with the villain Nine inside. The heroes were pursuing the villains, and Endeavor's attack caused the crash that freed Nine from the life-support capsule, inadvertently starting the conflict.

The chase sequence establishes the villains as a serious threat before the focus shifts to Nabu Island.

Twice used his own Quirk to create clones of the League of Villains members. When Endeavor destroyed the truck, the villains revealed themselves as clones born from Twice. This was part of the villains' escape plan, though the clones were destroyed in the crash.

The clone reveal during the truck crash introduces Twice's cloning ability as a plot element.

Class 1-A is dispatched to Nabu Island as part of a safety work program, giving students real hero experience while protecting a remote community. The peaceful mission becomes a deadly challenge when Nine and his gang invade, forcing the students to prove themselves as the next generation of heroes.

The initial calm on Nabu Island contrasts sharply with the sudden villain attack, emphasizing the unpredictability of hero work.

Nine's gang attacks Katsuma's father to steal his Quirk and test blood type compatibility. They discover that Katsuma possesses the specific Quirk with the right blood type needed for Nine's cure, making the child the target instead.

The attack on the father serves as the key clue that leads Nine to Katsuma.

The embers refer to the residual power of One For All that lingers after the main transfer. Even when Bakugo temporarily holds One For All, Izuku uses the remaining embers to cooperate in the fight, combining their efforts to defeat Nine.

The embers concept explains how both heroes can use One For All power simultaneously.

The Cell Activation Quirk is a special ability that Nine requires to cure his terminal illness. The disease developed as a side effect from the modifications he underwent to hold multiple Quirks. Without this cure, Nine would die from his condition.

Ujiko's experiments on Nine are revealed to have caused the illness, creating his urgent need for Katsuma's Quirk.

Class 1-A protects Katsuma and Mahoro because Nine specifically targets Katsuma for his healing Quirk. The siblings are innocent civilians, and keeping them safe becomes the students' primary mission alongside evacuating all islanders from Nabu Island.

Izuku's bond with the siblings early in the film establishes emotional stakes for their protection.