Luka stood before the wooden crates, his heartbeat still racing from his last sprint across the bridge. He had finally gotten used to controlling his speed, but breaking something?


    That was different.


    Sun clapped his hands together. “Alright, kid. Since you’re terrible at understanding normal explanations, let’s make this simple. Think of it like math.”


    Luka blinked. “Math?”


    Sun nodded. “Yeah. You know how force works, right?”


    Luka hesitated. “…No.”


    Sun sighed dramatically. “Of course you don’t. Alright, listen up.”


    He grabbed a small rock from the ground and tossed it lightly at Luka’s chest. It barely tapped him.


    “That didn’t hurt, right?”


    Luka shook his head.


    “Now watch.”


    Sun picked up another rock, but this time, he pulled his arm back fast and threw it.


    THWACK.


    The rock smacked Luka in the shoulder. He yelped, rubbing the sore spot.


    “Ow!”


    Sun grinned. “See the difference?”


    Luka frowned. “Because you threw it harder?”


    “Exactly,” Sun said. “But here’s the important part—the weight of the rock never changed.”


    Luka’s eyes widened slightly.


    Sun pointed at the crates. “The same thing applies to your body. A normal punch from you won’t do much. But if you add speed, your weight increases at the moment of impact. Momentum turns speed into power.”


    He tapped his mask. “Think of it like a math equation:


    Speed × Mass = Force


    The faster you go, the harder you hit. That’s why people can’t run full speed into a wall without breaking something.”


    Luka stared at the crates. “So if I go fast enough… I can break those?”


    Sun smirked. “If you do it right.”


    Luka clenched his fists. He took a deep breath, lowering his stance.


    “Alright,” Sun said, stepping back. “Let’s see it, kid.”


    The narrative has been taken without permission. Report any sightings.


    Luka erased his weight, just enough to move fast.


    He took off, sprinting forward, the wind rushing past his ears. He could feel his body moving faster than ever before.


    The crate was right in front of him—


    He swung his fist.


    CRACK—!


    The impact stopped him instantly.


    Pain shot through Luka’s arm. His knuckles throbbed.


    The crate didn’t break.


    Instead, Luka was the one who bounced back, landing hard on his rear.


    Sun burst out laughing.


    Luka winced, cradling his hand. “That hurt!”


    Sun wiped a fake tear from his eye. “Of course it did, you idiot! You forgot the second part!”


    Luka groaned. “What second part?”


    Sun crouched next to him. “You ran fast, yeah. But the moment you hit the crate, you stopped. All that speed died the second you punched.”


    Luka frowned. “Then… what did I do wrong?”


    “You hesitated,” Sun said. “Instead of following through, you held back at the last second. If you don’t commit, all that built-up power vanishes.”


    Luka stared at his bruised knuckles. “So I have to… keep going?”


    “Bingo,” Sun said, standing up. “Speed doesn’t just stop when you hit something. You have to let your whole body flow through the motion. Otherwise, you’re just slapping the crate with a fancy sprint.”


    Luka clenched his fists. Again.


    This time, he focused harder.


    He ran.


    Faster.


    His breath was steady, his body light.


    The crate was closer—


    He swung.


    BOOM!


    Luka missed.


    His fist barely grazed the side of the crate before his momentum carried him forward—


    CRASH.


    Luka tripped over his own feet and skidded across the dirt.


    Sun clicked his tongue. “Better. But still bad.”


    Luka groaned into the ground.


    Sun walked over, tapping his boot against Luka’s head. “What was the mistake this time?”


    Luka pushed himself up, spitting out dust. “I didn’t aim?”


    “Yep,” Sun said. “Speed means nothing if you don’t have control. You’re moving, but you’re not guiding that movement. Right now, you’re just running blindly and hoping it works.”


    Luka exhaled sharply. “Then how do I aim?”


    Sun smirked. “With your whole body.”


    He turned, facing the crate himself. Luka watched carefully.


    Sun took a step back—


    Then vanished.


    A dark blur streaked forward.


    BOOM.


    The crate shattered instantly, wood splinters flying everywhere.


    Sun didn’t stop moving. His fist followed through the motion, his body turning with the impact. He skidded to a slow stop, hands in his pockets.


    Luka’s jaw dropped.


    Sun turned back. “See? I didn’t just punch—I let my entire body carry the force. You have to move through the attack.”


    Luka clenched his fists. “Again.”


    Sun grinned. “That’s the spirit.”


    Luka ran.


    This time, he didn’t hesitate.


    He focused—not just on speed, but on his body. His arms. His feet. His breathing.


    He let it flow.


    BOOM!


    A loud crack echoed.


    Luka stumbled backward, his fist stinging—


    But this time, the crate had a dent.


    His heart raced.


    He did it.


    He cracked it.


    Sun clapped. “Now we’re getting somewhere.”


    Luka shook out his sore hand, grinning despite the pain.


    He barely had time to catch his breath from breaking the crate when Sun suddenly knelt down in front of him, pulling something out of his coat.


    It was a set of metal rings—thick, polished, and strangely futuristic.


    Luka frowned. “What’s that?”


    Sun smirked beneath his mask. “A little gift from Mina. It’s called a gravity regulator.”


    Before Luka could ask, Sun grabbed his wrist and snapped one ring around it. Then another.


    Clank.


    Luka’s legs buckled instantly.


    His knees slammed into the dirt, his arms yanking down as if someone had tied bricks to them.


    It was heavy.


    Luka gritted his teeth, his small fingers digging into the ground. “Wh-what the hell—?!”


    Sun chuckled, fastening the last two rings around Luka’s ankles. “They increase your personal gravity, kid. Your muscles are weak. You’re too skinny. This’ll fix that.”


    Luka tried to push himself up—but his arms shook violently. Every movement felt like he was being dragged down by an invisible force.


    He glared up at Sun. “This… sucks.”


    Sun patted Luka’s head. “Good. That means it’s working.”


    Luka scowled.


    Sun stepped back, crossing his arms. “Alright, here’s the deal. You’re not allowed to use your Jōki to enhance yourself. Not until something bad happens.”


    Luka blinked. “What do you mean ‘something bad happens’?!”


    Sun shrugged. “I mean if you’re about to get crushed, stabbed, or eaten—then you can use it. Otherwise, no enhancement. Just pure training.”


    Luka’s stomach sank.


    Sun clapped his hands together. “Okay! First step—stand up.”


    Luka clenched his jaw.


    His arms trembled as he tried to push off the ground, his muscles straining under the weight. He barely lifted himself an inch before his body collapsed again.


    Sun sighed. “Damn, kid. You really are weak.”


    Luka shot him a glare.


    Sun crouched down in front of him. “Listen, you wanna be fast, right? Wanna be strong?”


    Luka hesitated—then nodded.


    “Then get up,” Sun said simply.


    Luka gritted his teeth and tried again.


    One inch.


    Two inches.


    His arms shook violently, sweat dripping down his forehead.


    Sun watched patiently. “C’mon. Don’t tell me you’re gonna cry.”


    Luka gritted his teeth.


    Push.


    His body felt like lead. His muscles screamed.


    Push.


    His shoulders burned. His breath came out in sharp pants.


    Push.


    Finally—


    He stood.


    Luka wobbled, his legs trembling like a newborn deer, but he was standing.


    Sun grinned. “Not bad.”


    Luka glared. “This is hell.”


    Sun laughed, slapping Luka’s back hard enough to make him stumble. “Nah, kid. This is just the beginning.”