Collateral damage can best be defined as unintended destruction in a battle. It may include unnecessary harm to bystanders or the destruction of property. Both often occur simultaneously, with one often resulting in the other.
There have been many anime fights where the clash between a hero and villain has caused complete and unintended devastation, leaving death and ruin in the wake of the conflict.
10 Zoro's Fight Against Kaku Got The Tower Of Justice Cleaved In Half (One Piece)
Kaku was the second strongest member of CP9, falling short only of Lucci himself. Despite his ridiculous appearance, his giraffe form proved to be extremely lethal. A single rotation of his neck cleaved the entire Tower of Justice in half.
Realizing that he was overshadowed in the way of brute force, Zoro assumed a new stance with so much speed that it left after images of himself. It allowed him to cut through Kaku's iron body before he could cause any more wanton destruction.
9 Naruto & Sasuke Destroyed The Valley Of The End In Their Second Fight (Naruto)
The final clash between Naruto and Sasuke invited utter disaster. As Kurama fought the Susanoo in the Valley of the End, the statues of Madara and Hashirama were caught in the chaos and significantly damaged.
While this was symbolic of their eroding friendship, it also illustrated how much both shinobi had grown since Sasuke left the village. In their first battle, they barely managed to make a crack against the great stone monuments, let alone shatter them entirely.
8 No One Was Safe During The Phantom Troupe's Feud With The Yorknew Crime Families (Hunter X Hunter)
The feud between the Phantom Troupe and Yorknew crime families had serious repercussions. Not only were most of their battles in the middle of the street where innocent people could get hurt, but there were also several skirmishes across the city that maximized the chaos. Chrollo himself compared the spectacle to a symphony of destruction and could view it from near the top of a skyscraper.
Perhaps the greatest example of collateral damage comes from Uvogin's fight with the Shadow Beasts, where his screams ruptured the eardrums of everyone in the canyon.
7 Escanor's Battle With Estarossa Was So Intense That It Melted The Armor Off His Comrades (Seven Deadly Sins)
During the reclamation of Liones, Escanor confronted Estarossa and challenged him to a fight. They were evenly matched to a fault; the Lion Sin was so powerful that his sheer presence began to melt the armor of nearby knights, forcing them to disrobe.
It escalated further after the battle began. Not only did Escanor's fight destroy most of Liones' castle, he evaporated an entire lake with a single usage of the "Cruel Sun" ability.
6 Endeavor Disintegrated Tall Buildings In His Battle With High-End (My Hero Academia)
Endeavor's fight against High-End marked the beginning of his reign as the Symbol of Peace. However, it also caused massive destruction in a densely populated city, entailing that the heat hero had not abandoned his callous ways.
In an attempt to disintegrate the Nomu, Endeavor reduced a massive skyscraper to ash in a matter of seconds. Innumerable civilians would have plummeted to their deaths if Hawks wasn't nearby to save them with his detachable feathers. Fortunately, Endeavor had the sense to finish the battle in the sky, so as not to jeopardize the innocent further.
5 Eren's Fight With Lara Was Notorious For Its Civilian Casualties (Attack On Titan)
When the invasion of Liberio officially began, Eren didn't hesitate to attack the War Hammer Titan before she could fully transform. To him, collateral damage wasn't a consequence of the battle; it was the intended goal.
His fight against Lara sent debris scattering everywhere and frightened audience members who had gathered to watch Willy Tybur's speech into stampeding. They had no compunctions about trampling Udo to death, further cementing Gabi's belief that the Eldians were inherently sinful devils.
4 Entire Districts Were Razed In Tatsumi's Fight With The Emperor (Akame Ga Kill!)
As a last resort to preserve his reign, the Emperor entered his Imperial Arms and fought Tatsumi. He wielded weapons so destructive that they could simulate the effects of a nuclear blast, and as a consequence, there were thousands of unintended deaths in his efforts to catch his opponent.
Even after being defeated, the Emperor's hulking frame threatened to crush everyone directly below him. While Tatsumi managed to halt the metal husk, he overexerted himself doing so and died shortly after.
3 Nataku Almost Destroyed The Entire City In His Fight Against Shinra & Charon (Fire Force)
When Ritsu used nearby corpses as a foundation for turning Nataku into a massive infernal, the young boy's ailing mind was even further shattered. He lost control of his senses and attacked everyone nearby with enough power to destroy Tokyo itself.
Shinra braced for annihilation, only to find the most unlikely of saviors. Charon used his Ignition Ability to deflect Nataku's blast of energy to the moon. It left such a devastating impact that it was noticeably defaced once the dust had settled.
2 Innocent People Got Hurt In Jotaro's Fight With DIO (JoJo's Bizarre Adventure)
Since Jotaro's fight against DIO occurred in the city of Cairo, casualties were almost inevitable. The vampiric villain used an innocent person to chauffeur him across town and ensure that the Crusaders didn't escape. After his usefulness had ended, DIO murdered his hostage and left the car.
The city itself would also take a heavy beating. Kakyoin destroyed a clocktower, and DIO threw a massive bulldozer as a makeshift projectile weapon. When the dust cleared, it was virtually impossible to explain what happened without prior knowledge of Stands.
1 Akira's Fight With Ryo Destroyed The Entire World (Devilman Crybaby)
Despite his former friend's status as the devil himself, Akira did everything in his power to defeat him. Their battle - combined with the apocalyptic struggle between Earth's forces and Hell's armies - was so destructive that the world itself became cracked and uninhabitable.
The human race was exterminated in the widespread carnage that the demons unleashed, and in the end, even Akira would fall. Ryo only realized how much he cared for his friend after his death and once it was far too late to undo his actions.