The metallic clink of the heavy padlock felt deafening in the quiet dojo. Kenji's frail, calloused hands unwound the thick, rusted chains wrapped around the long black box. As the chains slipped off, they hit the wooden floorboards with a dull, heavy thud that vibrated through the soles of Zoro's bare feet.
Zoro didn't blink. The adrenaline from the fight outside had completely faded, replaced by a cold, sharp curiosity. He watched as his master pulled back the heavy, faded canvas.
Inside the box, there was no legendary, glowing katana. There was no beautifully crafted hilt or polished silver blade.
It was just... a slab of dark, ugly metal.
It was roughly shaped like a sword, but it was twice as thick as a normal katana and completely blunt. The surface was rough, absorbing the dim light of the room rather than reflecting it. It looked less like a weapon and more like a piece of industrial debris ripped straight from a construction site.
"In the old days, they called this a Suburito—a heavy wooden sword used purely for conditioning," Kenji said, his voice quiet, almost respectful. "But this one is not made of wood. It is forged from compressed high-density tungsten and hero-grade steel alloy. It has no edge. It has no grace."
Kenji stepped back, gesturing to the dark slab. "You said you need to cut through multi-ton machines made of reinforced armor. To cut such a thing, your body must first learn to endure its weight. Try to lift it."
Zoro stepped forward. The air around the box smelled of old oil and rust. He reached down with his right hand, wrapping his fingers around the rough, thick grip. He expected it to be heavy, maybe twenty or thirty kilograms.
He pulled upward.
Nothing happened.
The dark metal didn't even budge. It felt as if it were bolted to the very foundation of the earth. Zoro's brow furrowed. He released his grip, wiping a drop of sweat from his chin, and leaned down, grabbing the hilt with both hands. He widened his stance, dug his toes into the wooden floor, and took a deep breath.
Pull.
Zoro gritted his teeth. The veins in his forearms swelled, pressing against his skin like thick ropes. The muscles in his back coiled tightly. Slowly, agonizingly, the dark metal began to lift.
It wasn't just heavy; it felt actively malicious, as if gravity itself was fighting him. His wrists screamed in protest. He managed to lift it waist-high, his arms shaking violently under the sheer, impossible density of the weapon. His breathing became ragged, short gasps of air escaping his locked jaw.
"That is the exact weight of a one-pointer robot's arm," Kenji said, his gray eyes watching Zoro's trembling shoulders without an ounce of pity. "If your arms cannot bear this weight, your steel will shatter the moment it strikes them. This is not a sword, Zoro. It is a beast. If you cannot tame it, U.A. High is a graveyard for you."
Zoro didn't answer. He couldn't. Every ounce of his focus was dedicated to not letting the iron drop and shatter his own feet. Sweat stung his eyes. He tried to raise the iron slab into a basic overhead stance—the starting position for a standard swing.
His shoulders burned as if acid had been injected directly into his joints. The iron reached his chest, then stopped. His muscles locked up, simply refusing to push any further.
With a harsh gasp, Zoro's grip gave out.
The iron beast slipped from his sweaty palms. It crashed onto the floor, instantly splintering the thick wooden tatami frame and cracking the stone foundation beneath it. The impact echoed through the silent neighborhood like a gunshot.
Zoro dropped to his knees, his chest heaving as he stared at the dark metal embedded in the floor. His hands were bright red, trembling uncontrollably.
He had practiced swinging his wooden sword three thousand times a day. He thought his arms were forged in fire. But trying to lift this... it made him feel like a weak, untrained child. It made him feel Quirkless.
Kenji watched him in silence, waiting for the boy to make an excuse. He waited for the frustration, the anger, or the realization that the goal was impossible.
Instead, Zoro didn't look at his master. He didn't complain about the weight. He simply wiped the sweat from his eyes, slowly wrapped his raw, trembling hands back around the rough iron hilt, and pulled again.
This time, a low, guttural growl escaped his throat.
A microscopic, approving smile touched the old master's lips.
By the time the first rays of the morning sun crept over the horizon of Musutafu, the dojo's courtyard looked like a war zone. Deep craters and smashed stones littered the ground where the iron had fallen repeatedly.
Zoro was standing in the center of the ruin. He looked like he had been through a meat grinder. His hands were wrapped tightly in white bandages, though dark spots of blood were already blooming through the fabric. He was breathing heavily, his white shirt sticking to his skin.
But the iron beast was no longer on the ground.
It was resting on his shoulder. He was holding it. Barely, but he was holding it.
"The entrance exam is exactly three hundred days away," Kenji's voice drifted from the porch. The old man was holding a steaming cup of green tea, sitting comfortably on a cushion. "For the next three months, you will not touch a real blade. You will not practice forms. You will only swing that iron."
Zoro tightened his grip, ignoring the sharp sting of his torn blisters. "How many times a day?" he asked, his voice hoarse from dehydration.
"Until it feels lighter than a wooden stick," Kenji replied, taking a slow sip of his tea. Then, the old man reached beside him and picked up a massive, thick canvas backpack. He tossed it off the porch. It hit the dirt with a heavy, metallic thud, kicking up a cloud of dust.
Zoro looked at the backpack, then back at Kenji.
"Good. You can hold it," Kenji said, his voice flat. "Now, put that backpack on. It's filled with iron sand. I want you to carry the sword and run to the Takoba Municipal Beach and back before the city wakes up."
Zoro stared at his master. Takoba Beach was on the other side of the city. It was miles away. His legs were already shaking from the ankle weights he never took off. His arms were completely numb.
He looked at the iron beast on his shoulder, feeling the crushing weight of reality pressing down on him.
He didn't complain. He just walked over to the backpack.