The floor has become a sea of spikes that collide with one another in rapid succession, sharp waves of stone spiraling from every direction. Mirio has only managed to survive thanks to a combination of permeation phasing him through it all and One For All enhancing his endurance. He zips from spot to spot in an effort to escape the onslaught of cement spires, still trying to dodge them regardless of his ability to pass through the attacks; afterall, he needs an opening somewhere in order to turn tangible and retaliate, the point of persisting in battle otherwise pointless. Regardless, Chisaki's reassembly of the underground chamber is a complete overhaul to the environment. This is the Yakuza Leader's hometurf now more than ever.
Mirio uses permeation to survive being crushed by two slabs of stone slamming together, sandwiching him in the middle. When the blonde passes through and comes back out into the open, he's met by another wave of sharpened ground. Rather than phasing again, he meets the attack with a strike of his own. A One For All generated fist punches a hole through the floor and shatters the already fragmented features like glass. Chisaki controls the equilibrium with two ungloved hands pressed against the ground, contorting the chamber so that he's raised out of reach onto a platform.
Ripples of erosion careen across the ruptured terrain, intended to topple the tunnel and bury Mirio. Except, the young hero still has a youthful burst of energy left in his reserve, the kind that helps him to use the cement covered tidal wave as a launch pad for liftoff. He thrusts a fist forward to smash through the first barrier Chisaki throws up, spinning so that his momentum carries him further, and delivers a second punch into the second shield of stone. Debris litters the labyrinth as he flies upwards. Mirio blows away another layer of manipulated material before landing on top of the Yakuza Leader's self made platform.
"You're not getting away that easily", Mirio grins ear to ear as he rights himself to oppose the villain. Chisaki may as well be facing All Might himself while he's still in his prime. The young hero clenches each hand to form fists, preparing to punch his way forward again.
More fluctuation of the floor ensues, warding the blonde off. "Your kind disgusts me", Chisaki hisses with contempt as he watches his attacks countered time and time again, "You're a disease that needs to be purged!" The way Mirio maintains a smile, triumphant to the bitter end even when things are at their most critical … it drives Chisaki berserk.
The walls warp and the ceiling collapses, encasing All Might's successor in a tomb of the Yakuza's design. There's no plowing his way out of this one. Mirio phases through the ground that continuously reapplies itself until he surpasses its reach. Breaching the surface, he discharges the power he kept on reserve until then, a blowback of raw power circulating a whirlwind. A tornado twists the room apart as rapidly as it regrows its spikes. Chisaki roars as he releases a cataclysmic cascading counter to the airforce.
Spirals of spikes engage Mirio. Streaks of electricity jump from the blonde's back when he ducks down, One For All giving him yet another much needed boost to outmaneuver his opponent's playground. Digging deeper and deeper into the tunnels, the two twist as much as they curve their way into combat. Each fighter tries to get a read on the other; their movements shift the tides of the ring in which they battle. Stone shreds into shrapnel and rains down from above. Mirio matches the Yakuza's moves with some fancy footwork and manages to evade every spear thrown his way.
Training with Cementoss during his early U.A school days helps Mirio with the simple stuff like stone shields. It's the trickier and much deadlier attacks Chisaki throws at him that pushes him past his limits. But he didn't become part of Japan's top hero academy big three for nothing. Mirio catapults from another wave of the living ground, borrowing another teacher's skillset training to spring from the ceiling and rocket back down. He's no Gran Torino but the swift switchup gets him closer to capturing Chisaki. Just a little further now and he'll be within range.
More barriers arise between him and his enemy. "Okay, seriously, that move is getting kinda old!" Mirio presses through them the same as the last round of walls. Except, he doesn't find Chisaki on the other side of them. "Wha–", he's too distracted by the Yakuza's absence to sense the floor shifting beneath his feet. Swallowing his legs and pulling him under faster than quicksand can sink a person, the young hero finds himself in a predicament with the ground.
"Looking for me?", Chisaki emerges from an opening in the malleable material. He has one hand still maintaining contact with the tunnels, but his other is reaching forward. Mirio reacts on instinct, reeling away from the man's touch. While the young hero does avoid getting his face torn apart, he winds up trading his good looks for an arm. Chisaki uses his quirk, ripping the limb in various directions. "Got you", the Yakuza is happy to see a bloody mess for the first time in a long time.
Mirio tears himself away, losing only an arm, and saving the rest of his body. Not that he isn't in excruciating pain or completely horrified by the loss of a limb. He preserves his panic for later and instead pushes himself out of range from Chisaki with a burst of One For All. The damage is done and things only remain the same when Mirio is again bombarded by stone spires but he can see a light at the end of the tunnel. Literally. While that'd ordinarily be a bad thing, he'd like to believe this is a good sign. Since someone familiar is coming from it instead of pulling him towards it.
"Midoriya!", Mirio releases a breath of relief that he wasn't aware was being held in until now. Though, that doesn't last long. The boy brought the girl that Chisaki wants with him. "What are you doing here?!", he changes his mind when he realizes that they're basically playing right into Chisaki's hands so long as she's present.
"You looked like you could use a hand", Izuku makes light of the sight he sees when Mirio is forced to block an attack with one arm. Though that joke could have probably used a better sense of timing. "This was the only way to go", he explains the real reason why they wound be intercepting eachother.
"Eri", Chisaki stalls in his flow of the fluctuating floor when he spots the little girl clinging to Izuku. Mirio uses that pause as a rare chance to gain an advantage and darts forward but the opportunity passes as quickly as it came; a platform carries the villain to a safe distance while spikes keep the young hero busy. "So that's what this assault is about? You hope to take Eri away from me", the Yakuza Leader redirects his glare from Mirio to Izuku.
"Remember how you brought me back to life?", Izuku glances down at the girl in question. She shakily nods, too terrified to speak. He hopes the smile he offers her doesn't add to that fear but he's starting to feel a little feral as he reaches for the starter string on his sternum. "It can do other things too", he pushes her back so that she doesn't get injured by his bladed transformation. Chainsaws cut themselves out from his flesh so that they can be used to protect her.
"Such a vile disease you have!", Chisaki hisses with hatred when he witnesses the boy's change into Chainsaw Man. The amount of bloodshed makes the Yakuza break out into hives.
"Actually – It's thanks to this quirk that I was cured of a disease", Izuku corrects the villain before rushing in to meet Chisaki's attack head on. Chainsaws carve through stone, chipping away at the solid surface.
Mirio grinds his boots into the ground, gaining traction. Before Izuku can get impaled by a spire much faster than he is, the young hero vaults from the floor and whisks his ally out of harm's way. The two land near the girl named Eri, standing between her and Chisaki. "You need to get her out of here", Mirio uses the back of his hand to wipe sweat from his forehead while trying to recuperate.
Izuku does a doubletake, surprised by what he just heard. "And leave you to fight this guy alone? Don't you want my help?", he parries an incoming spike of stone to prove his point. But that was just one. There's a plentitude of others darting down at him.
Mirio moves the boy and the girl away, a bumpy ride being carried by one arm, but they evade the shower of spikes. "Not really", his voice breaks as he coughs out blood, "You're kinda getting in the way more than helping" And Izuku can't argue with that, surprised to see the guy fend off another attack with a whole arm missing.
"Fine", Izuku admits he's not going to be much help in this situation and focuses on Eri, "But you'd better not die on me!" He retracts the chainsaws on his arms so that he can carry her to safety.
"That WOULD be pretty bad, wouldn't it?" Mirio mutters under his breath a final joke before turning to face Chisaki. It's time that he gets serious. One For All circulates through his entire system, accumulating to as high a level as his body can currently handle.
Stone surges as Mirio's power does, meeting in the middle. Fissures sprout from the surface upon impact. Debris drags behind All Might's Successor as he flies forwards. Chisaki throws up a round of rocks, hoping to slow the assault. However, he achieves the opposite effect, granting Mirio a spring system to ricochet from. Last minute barriers mean nothing either. Mirio smashes the stone shields to smithereens.
Izuku carries Eri up onto a ledge where the tunnel isn't being controlled. Enough rubble has accumulated to create a hill for them to climb while simultaneously providing cover for their escape. Until a minor quake shakes their mountain, causing a small landslide. The blowback from the battle between Mirio and Chisaki gives away their position when they tumble back down to the bottom of the hall.
Chisaki redirects his attack to be a spiral of spikes heading in the direction of Izuku and Eri. Mirio stalls in his charge, shifting to fly back and save them. A race between the hero and the Yakuza leads to a stalemate. Mirio forces himself between the spires and his allies, taking the brunt of the blow. Without permeation, he's stabbed all across his body. More blood is shed than there was before.
"Fool", Chisaki presses his hands harder to the ground to give his spikes an added push. They spear through Mirio, extending to stab past the hero and towards the people behind him. He's stuck there, held in place. It was a worthless act of sacrifice.
Izuku moves in front of Eri, rereleasing the chainsaws in his arms. Met with a violent volley of swings, the spikes are severed as fast as they come. "I thought you weren't gonna worry about us?! GOOOO!", Izuku urges Mirio to abandon them despite the amount of strain it takes for him to keep up with Chisaki's wave of spires.
Realizing he has no choice but to charge ahead, Mirio nods, giving it his all. He phases through the spikes pinning him down so that he can be free to move again. And with a return to formula, uses One For All to pursue Chisaki. The Yakuza carries himself out of range with more ground manipulation. "YOU GET BACK HERE!", but Mirio presses on by pumping his legs even faster.
He channels only his strength, abandoning permeation for his final rush. Spikes jut out from below and above. One rips away a part of his left ear. Another knicks under his right armpit. Mirio yells at the top of his lungs while enduring every laceration from Chisaki's gauntlet. Until he's finally able to deal his own blow. A punch intended to blast the Yakuza away. "SMAAAAASH!", the single fist shatters stone in pursuit for its target.
A gunshot rings out. Mirio's fist stops short, an inch from colliding with Chisaki's face. Silence overtakes the remains of the room. Mirio's eyes expand as they stare ahead in shock. The Yakuza stares back, eyes equally broadened; when they begin to glaze over and close, only does the silence break by Chisaki choking on his own blood. Red spreads from the bullet hole in the villain's chest. Behind him, stands Sir Nighteye with a smoking pistol.
Nighteye surprisingly collapses first. It takes Mirio shoving past Chisaki to topple the Yakuza. "Sir!", Mirio drops down at his mentor's side. He can see the hero is suffering from a fatal gunshot wound of his own. Tears well in Mirio's eyes as he applies pressure to the injury, he knows it's a vain effort to stop the bleeding but tries anyways.
"Your arm…", Nighteye is as concerned as his protege when he sees the young hero is missing a limb. Not to mention all of the other severe injuries that he has. There's a lapse of judgment in which Nighteye wants to look into Mirio's future to ensure All Might's Successor still even has one.
Almost as though on cue, the villain from before returns to try and end it early. Chisaki springs forward from the ground, reaching for Mirio with his hands. He's screaming bloody murder with an intent to murder. His yell transitions to one of torment. Izuku steps in, swinging a chainsaw down to hack away at Chisaki's arms; the killing parts are severed at the elbow. The Yakuza hits the ground for good this time, his empire toppling with him.
"I really hate that guy", Izuku has half a mind to saw off more body parts than just that but restrains himself for Eri's sake. The little girl has returned to clinging onto his leg for dear life that he needs to retract his chainsaws again.
Mirio stares, stuck in a stupor. He breaks out of it by blinking, confirming what he just saw was indeed real. "Thanks for the save", his breathless voice matches his body when he finally allows himself to relax.
"Looks like it wasn't enough", but Izuku isn't quite as put at ease. He's looking past Mirio, at All Might's former sidekick. The man is dying.
"No..", Nighteye agrees. He reaches for them, straining to speak. "Makima mustn't have the girl", what he says when they draw closer is enough to shake them all to the core.
"Huh?", Izuku is barely able to speak either.
"She must have known about this… All of it", Mirio shares a look with Izuku as Nighteye pauses to cough, "She knew what would happen if we went in short supplied."
"You think she WANTED this?", Mirio has a hard time believing a Hero Association would be so underhanded. But when he looks at Izuku who's an agent of said association, he can see that the boy isn't quite as unconvinced by Nighteye's accusation.
"The only people to know about this operation are eliminated during an opp that's off the record and she gets Eri as a result", Izuku begins breaking down the same thought process that Nighteye must be having in his final moments. There's no way to confirm the theory but he has to admit it's a possibility as he says, "Maybe…"
"So what do we do?", Mirio can't see any light within the devastation of the underground tunnels anymore as he looks up with despair.
Nighteye turns his head to face Izuku, bloodshot eyes settling on the blood soaked boy. "You're the reason that child has a future", the hero reaches for Izuku with a shaky hand, "Allow me to please see yours…"
Izuku reels back at first, hesitant. But ultimately accepts the outstretched hand. He leans into the touch, allowing Nighteye to place a palm against his chest.
Near or far, what the hero sees drains all life from his eyes. It's unknown if his skin turns pale from terror or blood loss. Maybe Nighteye saw Pochita's future and not Izuku's. No matter the case, one thing's for certain. Mirai Sasaki has no words to convey his vision. There's no warning he can give. All he has to offer is death as he gives his life in the end.
"Sir…", Mirio hunches over as he cradles the corpse of his dead mentor. Izuku hangs his head, placing a hand on Eri's head to turn it away from the body.
