● I. THE JOURNEY: VIBRATIONS OF UNREST
The Shinkansen bullet train was a silver needle sewing its way through the dark fabric of the Japanese countryside. Inside the pressurized cabin, the air felt sterile, a sharp contrast to the raw, cedar-scented oxygen of the mountains Sherlock had just left. He sat by the window, his reflection ghostly against the glass. He looked different—his jaw was set firmer, and the "lazy heir" slouch had been replaced by the coiled tension of a predator.
Beside him, Thomas Itadori was a statue of grim focus. He wasn't looking at the scenery; he was staring at a tablet displaying the layout of Hosu City.
"We're entering a hornets' nest, Sherlock," Thomas said, his voice low enough to be drowned out by the hum of the train. "The Hero Killer isn't just a criminal. He's an ideology with a blade. He's been seen in Hosu three times in the last month. Every time he appears, a 'Top Hero' ends up in the intensive care unit—or a morgue."
Sherlock's mind immediately pulled up the file on Tensei Iida, also known as the Turbo Hero: Ingenium. He had analyzed the police reports during his break. The wounds were precise, designed to paralyze before they killed.
"My father mentioned the Commission is desperate to suppress the news," Sherlock noted. "But why send a 'Cleaner' like you? This seems like a task for a combat-heavy Pro like Endeavor."
Thomas turned the tablet toward Sherlock. It showed a map of the back-alley attacks. "Because Stain doesn't fight in the light. He fights in the friction-less gaps of society. The Commission wants him captured, yes, but they want it done quietly. They're afraid if he's caught in a public spectacle, his 'message' about the corruption of heroes will spread like a virus. I'm here to take him off the board before the public realizes there's a war for the soul of heroics happening in these alleys."
● II. The pattern of vengeance
"There's something else," Thomas added, his eyes narrowing. "Stain's last victim was Tensei Iida. He was a 'pure' hero by most standards, but Stain judged him as a fake. It was a brutal, one-sided slaughter. Tensei will never walk again."
Sherlock's breath hitched. He thought of Tenya Iida, the Class 1-A representative. He remembered Iida's rigid posture, his obsession with rules, and the terrifying silence that had enveloped him ever since the Sports Festival.
Tenya is in Hosu, Sherlock thought, his brain spinning a web of probability. He chose his internship with Manual—a mid-tier hero with a localized Quirk. It was a tactical error for a student of his caliber... unless it wasn't a mistake. It was a choice. A choice of proximity.
"Uncle," Sherlock said, his voice tightening. "Tenya Iida is here. If he finds Stain before a Pro does, he'll try to fight him. He'll try to avenge his brother."
Thomas sighed, leaning back against the headrest. "Then the boy is already dead. Stain has survived dozens of encounters with veterans. A student driven by rage is exactly the kind of 'fake' Stain enjoys carving up. If Iida finds him, the math of his survival drops to zero. He'll be a stain on the pavement before he can even fire his engines."
● III. ARRIVAL IN HOSU: THE SEARCH COMMENCES
The train hissed as it slid into the Hosu Station. The atmosphere in the city was palpable—a mixture of fear and forced normalcy. Pro Heroes patrolled the streets in pairs, their eyes scanning the rooftops.
As they stepped onto the platform, Sherlock felt the weight of his new arsenal. Underneath his compression suit, his pores were ready. His Origami Scouts were tucked into his belt, and his mind was a calibrated machine, ready to process the sensory data of a city under siege.
"We split up," Thomas commanded as they exited the station. "I'm heading to the precinct to coordinate the friction-locks on the main exits. You stay on the patrol routes. Observe. Do not engage. If you see a blue suit with engines in the legs, you call me immediately."
"I understand," Sherlock replied.
But as Thomas vanished into the crowd, Sherlock's logic took a different path. Thomas is looking for a villain. I am looking for a classmate.
Sherlock slipped into a side alley, away from the neon lights of the main thoroughfare. He knew Iida wouldn't be on the main streets. Iida would be where the shadows were deepest, searching for the man who had broken his family.
Tenya is driven by a singular, emotional variable, Sherlock reasoned, releasing his first Origami Insect into the air. He won't wait for a Pro. He thinks his grief makes him strong, but in this equation, grief is a weakness. I have to find him before he finds his grave.
He closed his eyes, the tactile link to the paper inscet activating. He felt the cold brick of the buildings, the vibration of distant footsteps, and the hum of the city. Somewhere in this maze of concrete, a "fake" hero was walking into a trap, and only a "Magician" had the eyes to see it coming.
● II. THE OUTBREAK
The transition from the tense quiet of the patrol to absolute chaos happened in a fraction of a second. A deafening roar tore through the Hosu skyline, followed by the screech of twisting metal and the shattering of glass. Sherlock stood at a street corner, his internal sensors immediately picking up the massive displacement of air. From the smoke of a derailed train, several nightmarish figures emerged—Nomus.
These weren't the lumbering giants of USJ; they were smaller, leaner, and possessed a frenetic, twitching energy. One had a winged physiology, its exposed brain pulsing under the orange glow of the streetlights as it snatched a civilian from the sidewalk.
Unbeknownst to Sherlock, the battle for Hosu's survival was already erupting across the rooftops. Gran Torino, a blur of yellow and white, was bouncing between buildings with the speed of a jet, intercepting a Nomu mid-air. Following closely behind was Izuku Midoriya, his body flickering with the emerald sparks of One For All: Full Cowl. Midoriya was a desperate streak of light, trying to keep pace with the veteran hero while his eyes searched the ground for his missing friend, Iida. They moved through the smoke like ghosts—Sherlock was mere blocks away, focused on the civilian sector, unaware that his rival was already in the heat of the fray.
The city had become a cacophony of sirens and screams. Heroes were struggling to contain the biological horrors while the police formed desperate perimeters. Sherlock didn't see the "Full Cowl" lightning or the elder hero's supersonic leaps; his gaze was fixed on the tactical map of the ground. He could feel the panic of the crowd—a variable that always threatened to collapse a rescue operation into a stampede.
"The distraction is too loud," Sherlock muttered, his hand tightening on a paper charm. "This is a smoke screen. Shigaraki wants the world to look here, which means the real threat is precisely where we aren't looking."
● III. THE SILENT EYES: FINDING THE ALLEYWAY
While the battle raged, Sherlock remained at Thomas's side. Thomas was a pillar of cold efficiency, using Friction Mastery to anchor sliding cars and prevent buildings from collapsing onto the fleeing public.
"Sherlock! Focus on the evacuation!" Thomas barked, his hands glowing as he redirected the kinetic energy of falling debris.
Sherlock nodded, but his mind was elsewhere. He reached into his tactical pouch and released his Origami Scouts. Instead of just searching for the villain, he deployed four of them to the local shelters. As the paper spiders scuttled over the heads of the crowd, Sherlock used them to "sense" the structural integrity of the evacuation tunnels and monitor for hidden Nomu threats, guiding people toward the safest exits through subtle vibrations.
However, two of his scouts remained under his direct command, slipping into the dark, neglected veins of the city. While he helped an elderly man reach a police barricade, Sherlock's consciousness was split. Where is Iida? The question pulsed in his mind like a heartbeat.
Logic dictates the hunt, Sherlock reasoned. A vengeful hunter doesn't seek a crowd. He seeks the stage of his brother's defeat. Tensei was attacked in a low-traffic district—a place where the absence of witnesses is a tool.
He pushed his scouts deeper into the 4th District, away from the Nomu's fire. He felt the cold, damp stone of the back alleys through the paper's legs. He felt the vibration of a trash can being knocked over. Then, his fingers twitched.
Scout 5 picked up a distinct, high-frequency rhythmic pulse. It wasn't the sound of the battle; it was the hum of cooling engines. Recipro Burst. And then, a sound that made Sherlock's stomach turn: the wet, heavy thud of a blade hitting a body, followed by the silence of a man who has lost his voice to shock.
"Uncle, I found him," Sherlock said, his voice dropping to a terrifying chill. "Iida is in the west alley of the 4th District. And he's not alone."
Thomas looked at the boy, seeing the emerald light in his eyes. "Go. I'll hold the line here. If you find the Hero Killer, Sherlock... don't try to be a hero. Just survive."
Sherlock didn't wait. He activated the Shikigami Dance, his body becoming a blur of white sheets as he vanished into the shadows of the alleyways.
● THE SHADOW OF HOSU: THE ENGINE'S GRIEF
The night air in Hosu City was thick with a suffocating tension. On the surface, the city lights flickered with the rhythm of a normal evening, but in the heart of Tenya Iida, there was only a cold, mechanical void. Since the day his brother, Tensei—the hero Ingenium—had been struck down, the world had lost its color. The rules, the propriety, and the noble ideals of UA High felt like distant echoes from a life that no longer belonged to him.
Iida walked several paces behind the Pro Hero Manual, his eyes hidden behind his visor, scanning every dark corner. Manual was talking about the importance of steady patrols and public safety, but Iida wasn't listening. He was hunting a ghost. He was looking for a man who wore rags and carried the stench of blood.
He's here, Iida thought, his fists clenching so hard his gloves groaned. The Hero Killer. He has to be here.
● THE NIGHTMARE BEGINS: THE NOMU ATTACK
The silence was shattered by a violent explosion that rocked the foundations of the district. Smoke billowed into the sky, dyed a hellish orange by the fires below. From the wreckage of a derailed train, three nightmarish creatures emerged. They were the Nomu—the same mindless, multi-quirk biological weapons that had laid waste to USJ.
One possessed a winged frame, its brain exposed to the night air, while another, a hulking mass of muscle, began to tear through the street-side buildings. Panic erupted instantly.
"Iida! Stay with the police and help with the evacuation!" Manual shouted, his water-based Quirk ready for action as he rushed toward the fires.
But Iida didn't move toward the screams. Amidst the chaos, a flicker of movement in a far-off, darkened alleyway caught his eye. It was a silhouette that didn't belong to a civilian or a Nomu. It was the silhouette of a man who moved with a jagged, predatory grace.
Without a word, Iida turned his back on the disaster. He ignited his engines, the blue flames of his Recipro Burst casting long, distorted shadows against the brick walls as he sprinted away from the light and into the darkness.
● THE ENCOUNTER IN THE DARK
Deep within a dead-end alleyway, far from the reach of the sirens, a Pro Hero named Native lay slumped against a dumpster, his body paralyzed and bleeding. Standing over him was the Hero Killer: Stain. He looked exactly like the reports: a tattered red scarf that fluttered like a tongue, a mask made of bandages, and a serrated katana that seemed to drink the moonlight.
"You heroes are all the same," Stain rasped, his voice a low, terrifying growl. "Driven by fame, money, and your own ego. You've forgotten what it means to be a sacrifice. To cleanse this society, the fakes must be weeded out."
Just as Stain raised his blade to deliver the final blow to Native, a blue streak of fire roared into the alley.
"STOP!"
Iida's kick connected with Stain's blade, knocking it back. Iida skidded to a halt, his engines hissing steam, his breath coming in ragged gasps of fury.
Stain didn't look surprised. He looked disappointed. "Another one? A child wearing the face of a hero."
"I am the younger brother of the man you struck down!" Iida screamed, his voice breaking with a decade of repressed grief. "The hero you ruined! I am Ingenium! And I will be the one to end you!"
Stain's red eyes narrowed. He looked at Iida—not at his armor, but at his soul. "Ingenium? That hero died for the sake of others. But you... you aren't here to save this man." Stain pointed his blade at the bleeding Native. "You aren't even looking at him. Your eyes are full of yourself. You are the purest form of a 'fake'—a murderer masquerading as a hero."
"Shut up!" Iida lunged forward, his engines screaming. But Stain was faster. With a movement that defied the physics of the alley, Stain dodged the kick, drew a hidden dagger, and sliced a shallow line across Iida's arm.
Iida prepared to counter-attack, but suddenly, his body locked. His muscles refused to obey. He collapsed to the cold, damp stone, his face hitting the dirt.
"What... why can't I move?" Iida gasped, his eyes wide with terror.
"My Quirk: Bloodcurdle," Stain whispered, stepping over Iida's prone form. He licked the blood from his dagger. "By consuming the blood of my target, I can paralyze them. The duration depends on the blood type, but for you... it's more than enough time."
Stain placed his foot on Iida's head, pressing it into the ground. "You're a child playing at revenge. You came here to kill me for your own satisfaction, while a man lay dying behind you. You are a cancer on this society, boy. Die."
● THE UNEXPECTED LIGHT
Just as Stain's blade began to descend toward Iida's neck, a flash of emerald light illuminated the alleyway.
"SMASH!"
A fist encased in green electricity slammed into Stain's face, sending the Hero Killer skidding back across the pavement. Izuku Midoriya landed in front of Iida, his body sparking with Full Cowl, his expression one of absolute, desperate resolve.
"Iida-kun! I found you!" Midoriya yelled, not taking his eyes off Stain.
"Midoriya... why? Go away! This has nothing to do with you!" Iida sobbed from the ground, the weight of his failure crushing him more than Stain's foot ever could.
"It has everything to do with me!" Midoriya countered. "Because heroes are supposed to meddle where they aren't invited!"
Stain stood up, wiping a trail of blood from his lip. A dark, twisted smile spread across his face. "Now... this one... this one has the eyes of a real hero. Come, child. Show me if your conviction is stronger than my blade."
The air in the alleyway grew cold as the three-way standoff began. The Hero Killer, the broken Venger, and the Boy with the flickering light.