The battle between Izuku Midoriya (Deku) and Kai Chisaki (Overhaul) is one of the most impactful and emotional fights in My Hero Academia. Taking place during the Shie Hassaikai Arc, this fight highlights Deku’s explosive growth as a hero, Eri’s critical role in changing fate, and the terrifying destructive power of Overhaul’s quirk. It remains a fan-favorite clash because of its intensity, speed, emotional stakes, and the unforgettable transformation: Deku at 100% Full Cowling. Hero Licenses & Training Process
This breakdown covers the complete sequence of the battle, the strategies used, the turning points, and why this fight changed the future of hero society forever.
Build-Up to the Battle
The Shie Hassaikai raid begins when heroes team up to rescue Eri, a young girl whose quirk is being exploited to create anti-quirk bullets. Overhaul views Eri as a tool, while Deku sees her as someone who desperately needs saving.
Throughout earlier encounters:
- Deku failed to save Eri in the hallway
- Overhaul warned heroes to stay out of his business
- Mirio (Lemillion) fought Overhaul alone to protect Eri
By the time Deku confronts Overhaul, the emotional stakes are at their peak. He’s not just fighting a villain—he’s fighting a monster who treats an innocent child as an object.
Overhaul’s Quirk and Power Advantage
Overhaul’s quirk gives him:
- Complete control over matter
- Ability to disassemble and reassemble anything he touches
- Power to merge with others, enhancing his form
In the final phase of the battle, Overhaul fuses with Rikiya Katsukame and later with other henchmen, becoming a monstrous, multi-limbed titan with overwhelming strength.
His powers make him nearly unbeatable in close combat.
Deku’s Early Struggle
Even as a trained U.A. student, Deku faces several issues:
- Limited ability to use One For All at high percentages
- His body cannot withstand long-term high-output attacks
- Overhaul’s quirk gives him an unpredictable advantage
Initially, Deku fights at 20%–30% Full Cowling, but he is pushed back continuously. Overhaul’s attacks are lethal, fast, and destructive.
The turning point comes when Eri begins rewinding Deku’s injuries, allowing him to push All For One to unseen levels.
Eri’s Role – The Game Changer
Eri’s quirk, Rewind, allows her to reverse the state of a living being:
- healing injuries
- restoring broken limbs
- reverting bodies
But she cannot control it, making it dangerous.
However, during the fight, Eri instinctively activates her quirk to save Deku from Overhaul’s fatal strike. Her power rapidly rewinds Deku’s injuries, letting him use One For All at 100% without damaging his body.
This combination of powers is described as:
“The power to twist fate itself.”
At this moment, Deku becomes stronger than ever before—faster than sound, agile beyond human limits, and powerful enough to go toe-to-toe with a fully fused Overhaul.
Deku at 100% – The Fight Turns Around
Once Eri stabilizes her hold on Deku, the fight transforms instantly.
Deku’s advantages at 100% Full Cowling:
- Unmatched speed
- Airborne mobility
- Crushing striking power
- Ability to outmaneuver Overhaul’s mutated forms
Deku becomes a blur of green lightning, launching blow after blow. Overhaul tries to reconstruct himself mid-fight, but Deku shatters every attempt.
Overhaul’s Final Form
Desperate, Overhaul fuses with more material and transforms into a massive, dragon-like creature. His size increases; his limbs stretch out; he becomes a quirk-enhanced monster capable of destroying entire hallways with a single attack.
But his main weakness remains:
- He must touch something to activate his quirk
- Deku’s speed makes direct contact impossible
Overhaul can’t keep up with Deku’s new speed and precision.
The Defining Moment – “You can be saved!”
The emotional heart of the fight is Eri’s fear and trauma.
As she cries, thinking she is harming Deku, he reassures her mid-battle:
“I won’t let go of you. I will save you!”
This moment strengthens Eri’s resolve and stabilizes her quirk output, giving Deku complete freedom to end the battle.
The Finishing Blow – “100% Detroit Smash”
The final attack is iconic.
Deku propels himself above Overhaul using air pressure, channels the full might of One For All, and delivers a colossal 100% Detroit Smash from the sky.
The impact is so powerful that:
- Overhaul’s fused form shatters
- His quirk loses control
- His monster body crumbles
- Eri is safely secured by Mirio and the heroes
Deku’s blow officially ends the battle.
Aftermath of the Fight
For Deku:
- He experiences the consequences of Eri’s uncontrolled rewind
- Other heroes help stop the quirk before it rewinds him out of existence
- He shows the true potential of One For All
For Eri:
- She escapes years of abuse
- Begins living at U.A.
- Starts learning to control her quirk
For Overhaul:
- He is arrested
- His arms are destroyed by Shigaraki
- His criminal operations collapse
This battle becomes a turning point in hero society and solidifies Deku as a future top hero.
Conclusion
The battle between Deku and Overhaul stands as one of the most powerful moments in My Hero Academia, combining emotional depth with explosive action. It showcases Deku’s evolution from a determined student to a hero capable of changing fate itself. With Eri’s Rewind supporting him, Deku finally unleashes the true potential of One For All at 100%, overcoming impossible odds and defeating one of the series’ most dangerous villains.
FAQs
Q1: Why is the Deku vs Overhaul fight so important in My Hero Academia?
A: The fight is a major turning point where Deku uses One For All at 100% for the first time with Eri’s help. It also marks Eri’s rescue and the fall of the Shie Hassaikai organization.
Q2: How does Deku use 100% Full Cowling without getting injured?
A: Eri’s Rewind quirk constantly heals and restores Deku’s body, allowing him to unleash 100% power without breaking his bones.
Q3: What makes Overhaul such a dangerous villain?
A: Overhaul’s quirk lets him dismantle and reconstruct anything he touches, including merging with others to gain monstrous forms. This gives him extreme offensive power and adaptability.
Q4: What role does Eri play during the fight?
A: Eri’s Rewind ability keeps Deku alive and restores him from any damage. Her emotional breakthrough helps stabilize her quirk, enabling Deku to maintain 100% power.
Q5: How does the battle end?
A: Deku overwhelms Overhaul with his unmatched speed and strength, finishing the fight with a massive 100% Detroit Smash that breaks Overhaul’s fused form.