Izuku Midoriya vs. Kai Chisaki

Izuku Midoriya vs. Kai Chisaki is the final battle fought between U.A. Student Izuku Midoriya against the Eight Precepts of Death's leader Kai Chisaki during the climax of the Shie Hassaikai Raid.

Eri helps Deku maximize his power to combat Overhaul's mon while fused with Rikiya Katsukame.

Prologue
Seeds of hope sewn by Lemillion have sprouted, giving Eri the determination to save those around her. She leaps into Deku's arms and he promises not to let go of her this time. Overhaul looks down at them from a stone pillar and demands Eri return to him. He destroys his own footing and descends at his enemy.

Deku knows he can't dodge Overhaul in mid-air, but he refuses to let go of Eri. He recalls Mirio asking what kind of hero Izuku wanted to become. This fills Deku with determination and winds up a counter-kick while Overhaul attacks by creating spikes that rush his targets. However, Deku creates a shockwave that propels him and Eri to the surface while still in the middle of his swing. He surmises that he used too much of One For All and it sent him flying in the same manner All Might uses New Hampshire Smash.

Aggravated, Overhaul calls out to Eri. He tells her that he needs her to fulfill his ambitions and then fuses himself with Rikiya Katsukame's unconscious body. Deku lands above ground surprised he didn't break his body despite going over his limit. As soon as Eri lets go of him, Deku feels the repercussions. Overhaul announces that Eri can't control her power and rises out of the cavern in a monstrous kaiju-like form.

Overhaul explains that Eri's Quirk allows her to rewind people. He claims that Deku will disappear if he continues to cling to her. Overhaul tells Eri that she's cursed and says the only way to stop her is with his disassembly. Deku refuses to return Eri. He puts her on his back and wraps Mirio's cape around him to bind them together.

Deku surmises that Eri's Quirk stopped him from feeling the pain from overusing One For All. He calls her Quirk kind, which brings Eri to tears. Deku states that Eri can heal him with blinding speed, but if he can accumulate injuries at an even higher rate then he can avoid rewinding to far. Deku asks that Eri lends him her power as he unleashes One For All: Full Cowl at 100%!

Battle
Overhaul makes wild claims that Deku and Eri don't understand the importance of her power. He researched extensively to develop the Quirk-Destroying Bullets and maximized Eri's Quirk's effectiveness. Overhaul believes Eri's curse can return people to the normalcy humans had before the Quirk phenomenon. Irate, the gigantic eight-armed monster attacks Deku by reshaping the land into giant scale trusted lances.

Within the blink of an eye, Deku bypasses all of the Overhaul's attacks and kicks the massive beast high into the air. Eri's power is getting more powerful as she's going all out to help her hero. Infuriated that no one understands his ideas, Overhaul goes right back at the young hero and transforms his giant body into a typhoon of mass.

Deku instantly flies through Overhaul's attack and break it apart completely. He knows there's a time lapse between Overhaul is able to heal himself after taking a hit. With his newfound speed, Deku exploits Overhaul's weakness with a powerful barrage of punches at using 100% of One For All. As Sir Nighteye watches on, he realizes that Deku is changing the destined future that he foresaw. Deku believes that if cannot save a little girl right in front of him, then he may never become a hero who can save everyone. Deku delivers an emphatic final blow to strike back with beliefs of his own.