One Day Later — U.A. High School, Pre-Festival Briefing Room
The room buzzed with tension, far more than usual for a pre-event briefing. Eraserhead stood at the front, arms crossed, eyes sharp despite the dark circles beneath them. Present Mic leaned against the wall, quiet for once. The students of Class 1-A shifted in their seats, sensing something was off.
"Before we begin the Sports Festival preparations," Eraserhead said, voice low and flat, "I need to inform you of a new directive from the Hero Public Safety Commission."
A projector hummed to life behind him. The screen lit up—not with the usual festival schedule, but a photo: the cratered remains of a street in Osaka, smoke still rising from it. Another image—Koji's twisted, bloodied corpse beneath a collapsed sign in Shibuya. A close-up of a vial filled with a glowing red liquid.
"There's a new drug on the black market. It's called Scarlet Rush. Enhances quirks temporarily. Unstable. Highly infectious".
A ripple of alarm ran through the students. Bakugo leaned forward, eyes narrowing. Midoriya took frantic notes. Todoroki's hand tensed at the table's edge. Uraraka looked at Iida, confused and worried.
"Is this… like Trigger?" Yaoyorozu asked, her voice hesitant.
"No," Eraserhead said. "Trigger affects brain chemistry. This stuff rewrites people. Their bodies, their minds. It doesn't just amplify—it mutates."
A pause.
"Is it a villain group?" Midoriya asked.
Eraserhead looked at him. "That's still being investigated. But we have a name. Mazoku. He's not just distributing it—he's growing it."
"Growing?" Kirishima asked, eyebrows raised. "Like… plants?"
"Something like that but you kiddies don't have anything to worry about," Present Mic said with a goofy smile on his face, breaking the tension
The class fell silent.
"The Sports Festival will still happen," Eraserhead continued. "But you'll see more security. Pros, Commission agents. Stay alert. Anyone acting off, any red veins under the skin—report it immediately. No hero work. No confrontations. Leave that to us."
A beat of silence.
"But what if it spreads here?" Kaminari asked.
Eraserhead looked out at the class. "Then we fight."
—————-
Elsewhere — Nagoya Underground
A lab lit in dull red. The walls throbbed like muscle. Pods lined the corridor, each one containing a partially-formed figure—mutated, quirk-enhanced, twitching with life.
Mazoku moved like smoke through the chamber, silent and curious. His eyes flicked from pod to pod, gauging progress.
Beside him, Aika floated midair, threads of crimson paper spiraling around her like a protective cocoon. Her eyes were empty. Her body trembled, torn between what she was and what she was becoming.
"She still resists," one of the twisted attendants rasped, part-human, part-demon"
Mazoku placed two fingers on Aika's temple. Her breathing slowed.
"She won't for long."
He turned toward a central column—clear and filled with Scarlet Rush pulsing like a heartbeat. Dozens of quirk signatures echoed from it. Stolen. Mutated. Stored.
"Begin distribution Phase Two. I want this in every major city before the Sports Festival begins. Let them gather and celebrate."
Aika stirred behind him.
"Let them watch their champions fall."
Hero Public Safety Commission — Secure Briefing Room
Monitors flared with incident reports: Osaka. Kyoto. Hiroshima. All showing enhanced individuals losing control, attacking civilians or collapsing in agony.
"This is accelerating," the sharp woman from Mirko's room said, now standing at a roundtable surrounded by the Commission's top brass and several Pro Heroes. "We estimate several dozen doses are already in circulation."
Endeavor slammed a fist on the table. "You said we had time."
"We were wrong."
Best Jeanist looked toward a red-highlighted cluster on the map. "He's spreading outward from Aokusa. A central hive?"
"We believe so," the agent replied. "A living one."
"I want a squad deployed now," Ryukyu said. "Before it gets worse."
"It's already worse," said Hawks, stepping in late. His coat was soaked, his wings tattered. "I just intercepted a batch of twenty vials being smuggled through Sapporo. All the dealers were already infected. Smiled right before they burst."
He tossed a bloodstained vial on the table.
"Scarlet Rush isn't a drug. It's some sort of sick message."
The room fell into silence again.
Then the lead agent said, "We need to send one back."
Everyone turned.
"We need to capture a host. Alive. See how far it goes. And if we can reverse it."
No one volunteered.
Until Mirko's voice crackled through the comms.
"Send me."
Forest Edge — Near Aokusa
A black transport truck idled in the dark.
Inside sat a small squad of Pros: Mirko, patched up and burning with rage. Rock Lock. Mandalay and the rest of the wild wild pussycats.
Mirko tightened the strap oh her boots
"I'm getting my blood back," she said coldly.
The doors opened.
The forest welcomed them.
————-
Day of the U.A. Sports Festival — Hero Arena, Musutafu
The stadium roared with excitement. Cameras panned across thousands of fans waving flags, children in All Might merchandise, banners fluttering in the wind. The sky was clear. On the surface, all was normal.
Midnight strutted to center stage, her usual smirk in place, mic in hand.
"WELCOME to the U.A. Sports Festival!"
The crowd erupted.
High in the stands, a row of pro heroes, Commission observers, and private security agents stood posted. Tension buzzed beneath their composure. Everyone was smiling. But eyes scanned the crowd. Earpieces whispered nonstop.
Down below, Class 1-A gathered in the prep area. The tension hit differently this year. Not from competition, but the invisible weight pressing in from above.
Midoriya stood near Todoroki and Uraraka, deep in thought. He'd heard All Might whisper something urgent to Aizawa earlier—something about a "siege" He hadn't asked questions.
Bakugo cracked his knuckles. "You all better not hold back."
"No one plans to," Todoroki replied calmly.
"Good," Bakugo snapped
The giant screen lit up with student profiles as the first obstacle course challenge was announced. The crowd cheered again.
But just as the gates began to open—
A scream echoed from the bleachers.
Everyone froze.
A young man in the crowd—third row, section 4B—jerked upright, clutching his face. His skin rippled. His veins pulsed red. He dropped to his knees, convulsing.
Then he exploded outward in a burst of sinew and liquid flame, his body shifting into something inhuman. He roared and leapt from the stands, straight into the field.
Chaos erupted.
More screams followed. Four others, scattered across the stadium, began to transform—each one a ticking bomb of quirk overload and Crimson corruption.
The announcers fell silent.
Aizawa was already in motion, erasing quirks mid-air, shouting orders.
"Iida! Get the students back inside—NOW!"
Security barriers slammed shut. Pro heroes launched from the stands. Cementoss formed walls. Midnight dropped her mic and activated her quirk, trying to lull the nearest mutant into sleep.
It didn't work.
One of the infected—someone who once had a minor duplication quirk—was now splitting into dozens of twitching, screaming copies, crawling over each other like insects.
Midoriya stared in horror.
"This was coordinated," Todoroki screamed, already encasing a lunging attacker in ice. "This isn't random."
"Damn right it's not!" Bakugo blasted forward, knocking one of the red-eyed creatures out of the air with a violent BOOM.
Above, the Commission scrambled, pulling kids out of the field, deploying suppression tech.
Same Time — Forest Depths, Near the Underground Facility
It was quiet in the forest.
Too quiet.
Mirko crouched in the undergrowth, eyes scanning the grotesque terrain. Her squad followed behind her: Rock Lock, Volt, and Mandalay, their expressions taut with focus.
The forest had changed.
Vines pulsed like arteries. Trees bent unnaturally toward a point deeper in the woods. The air stank of blood and rot.
"Motion ahead," Mandalay whispered, her telepathy reaching the group. "Three figures. Mutated. Not aware of us yet."
Mirko gave a small nod.
"Stick to the shadows. We're not here to fight unless we have to. The lab's up ahead—below ground. That's where the heart is."
They moved swiftly, bypassing twitching sentries whose bodies had warped under Scarlet Rush. One had no eyes. Another dragged two massive arms behind him. None of them spoke. Just stood. Waiting.
They reached a clearing.
At its center: a massive organic structure, shaped like a half-buried spine. Ribs jutted from the soil, arching like a cathedral of bone. At the base, a blackened maw, pulsing slowly. The entrance.
The group stopped inwardly all sharing the same feeling of disgust and repulsion.
Mirko stepped forward.
"No turning back now."
They entered the maze once again
And the forest swallowed the light behind them.