Did I Get Reincarnated as a Supporting Character?

The fluorescent hum of the convenience store buzzed in Sung-Min's ears as he shuffled down the snack aisle, his sneakers scuffing against the worn linoleum. It was past midnight, and the world outside the glass doors was a blur of neon lights and drizzle. He yawned, rubbing at the bags under his eyes with one hand while the other clutched a crumpled energy drink can. Twenty-three years old, overworked, underpaid, and perpetually single—his life was a masterpiece of mediocrity. A data entry clerk by day, a hopeless romantic by night, he spent his free hours buried in novels, dreaming of a life less ordinary.

Tonight, though, he'd finished something special: Eternal Bonds of the Crimson Blade, a sprawling fantasy romance harem novel that had consumed his last three months. It had everything—dashing heroes, breathtaking heroines, intricate magic systems, and a prestigious academy that churned out legends. The protagonist, Kang-Jae, was every reader's dream: tall, brooding, and blessed with a chiseled jawline that could cut glass. Sung-Min had sighed through the final chapter, envying Kang-Jae's effortless charm and the parade of women who fell at his feet. He'd even laughed at the side characters—those poor fools who existed only to be stepped on by the hero's greatness. One in particular, some nobody named Min-Sung, had stuck in his mind: a weakling who got humiliated in a duel and faded into obscurity by chapter ten.

"Man, I'd do better than that guy," Sung-Min muttered to himself, tossing the empty can into a recycling bin. He grabbed a bag of spicy chips and headed for the counter, his mind still half-lost in the novel's world. "At least I'd try to make something of myself."

The cashier barely glanced at him as he paid, and Sung-Min stepped out into the damp night, the bag crinkling under his arm. He didn't see the truck until it was too late—a delivery vehicle careening around the corner, tires squealing on wet asphalt. There was a flash of headlights, a jolt of pain, and then—nothing.

When Sung-Min opened his eyes, he wasn't on a hospital bed or floating in some ethereal void. He was sprawled face-down in the dirt, the scent of grass and pine needles sharp in his nose. His head throbbed like someone had taken a hammer to it, and his mouth tasted faintly of copper. Groaning, he pushed himself up, blinking against the sunlight filtering through towering trees. His hands—smaller than he remembered, softer—pressed into the earth, and a strange weight tugged at his chest.

"What the hell…?" His voice came out higher, smoother, not the gravelly rasp he'd grown used to after years of late-night coffee runs. Panic clawed at him as he staggered to his feet, brushing off a tunic that definitely wasn't his oversized hoodie. It was coarse, brown, and tied with a leather belt—something straight out of a medieval cosplay convention. He stumbled toward a nearby stream, its surface shimmering like a mirror, and froze at the reflection staring back.

Brown hair—messy, shoulder-length, and streaked with dirt—framed a face that wasn't his own. Emerald-green eyes, wide and startlingly bright, blinked in disbelief. His jaw was softer, his cheeks still rounded with youth, and his body… Sung-Min glanced down, patting himself with trembling hands. Thin arms, narrow shoulders, a frame that looked like it hadn't seen a gym—or a decent meal—in years. He was a twig, a scrawny teenager who'd collapse under a stiff breeze.

"No way," he whispered, his heart hammering. "This isn't… I'm not…" He trailed off, a memory flickering to life—Eternal Bonds of the Crimson Blade. The forest, the tunic, the stream—it was all too familiar. He'd read this exact scene in chapter one, when Kang-Jae woke up after a training accident. But Kang-Jae had been muscular, golden-haired, and oozing charisma. This body? This was no protagonist.

A cold realization sank into his gut. He wasn't Kang-Jae. He spun around, scanning the trees, half-expecting a system window or a disembodied voice to explain his predicament. Nothing came. Just the rustle of leaves and the distant cry of a bird. Then it hit him—Min-Sung, the pathetic side character who'd gotten his ass handed to him in a duel. Brown hair, green eyes, weak as a kitten. Sung-Min—no, Min-Sung—dropped to his knees, a hysterical laugh bubbling up.

"I'm a damn supporting character?" he choked out, clutching his head. "Of all the people to reincarnate as, I get him? The guy who trips over his own sword and gets laughed out of the story?"

He sat there for a moment, letting the absurdity wash over him. Death by truck, rebirth in a novel—it was the kind of plot twist he'd scoff at in a review. But the dirt under his nails was real, the ache in his legs was real, and the faint hum of magic in the air—sharp and electric—was definitely real. He'd read enough isekai to know the drill: he was stuck here, in a world of magic, monsters, and a harem of women who'd never look twice at a nobody like Min-Sung.

Unless…

Sung-Min's eyes narrowed as he stood, brushing off his tunic. He knew this story inside and out—every plot point, every character arc, every steamy scene that had made him blush at 2 a.m. Min-Sung was supposed to fade into the background, a footnote in Kang-Jae's legend. But Sung-Min wasn't Min-Sung, not really. He had his old life's memories, his stubborn streak, and a brain that refused to roll over and accept defeat.

"Screw the script," he muttered, clenching his fists. "I'm not here to be a punching bag."

His gaze drifted upward, past the treetops, where he knew the academy loomed on the horizon. Cresthaven Academy—the beating heart of this world, a sprawling fortress of stone and spires where the elite honed their skills and forged their destinies. Nobles, prodigies, and warriors gathered there, their rivalries as deadly as their magic. Min-Sung had enrolled as a lowborn nobody, scraping by on a scholarship, only to flunk out after his humiliating duel. But Sung-Min? He'd make it work. He'd claw his way up, turn this weak body into something strong, and rewrite his fate.

A twig snapped behind him, and he whirled around, heart leaping into his throat. A figure stepped from the shadows—a girl, her silver hair glinting in the sunlight, her violet eyes sharp and curious. She wore the academy's uniform, a fitted blue tunic with gold trim, and carried a staff that pulsed faintly with mana. Sung-Min's breath caught. He knew her—Liora Veyne, one of Kang-Jae's future love interests, a prodigy who'd barely spared Min-Sung a glance in the original story.

"You're late," she said, her voice cool and clipped. "The entrance exam starts in an hour. If you're planning to stumble through it like that, don't bother showing up."

Sung-Min blinked, his mind racing. This wasn't in the book—Min-Sung had already been at the academy, floundering in his first semester. Had his arrival shifted something? He straightened, forcing a grin despite the sweat prickling his neck. "Wouldn't dream of missing it," he said, his tone lighter than he felt. "Name's Min-Sung. Guess we'll be seeing a lot of each other."

Liora raised an eyebrow, unimpressed, then turned and strode off toward the academy's distant silhouette. Sung-Min watched her go, his pulse thrumming with a mix of dread and exhilaration. The game had changed, and he was no longer just a spectator. Weak body or not, he'd make Cresthaven his stage—and heaven help anyone who tried to write him off.