The world had once been a fragile tapestry of fragile alliances, where governments patted themselves on the back for maintaining a semblance of peace. That was before the Cataclysm—September 21, 2015, exactly ten years ago today. A toxic gas, born from some classified experiment gone catastrophically wrong, erupted from hidden facilities across the globe. It wasn't a weapon, or so the official stories claimed; it was an accident, a "quantum anomaly" tied to experimental energy sources. But the truth didn't matter. The gas spread like a plague, invisible and insidious, seeping into lungs, bloodstreams, and souls.
By dawn the next day, humanity awoke to chaos. Mana—raw, ethereal energy—surged through every living being. Hearts pulsed not just with blood, but with this new force, circulating it like a second lifeblood. Some manifested flames from their fingertips, others bent shadows or shattered stone with a thought. At first, it was hailed as evolution, a gift. But greed has a way of twisting gifts into curses.
Countries with vast resources—America's endless labs, China's disciplined masses, Russia's unforgiving terrains—harnessed mana faster. Borders dissolved into battlegrounds as nations vied for "Mana Veins," natural hotspots where the energy pooled, amplifying powers tenfold. The United States unleashed storms of telekinetic barrages on Canadian frontiers, claiming northern Veins as their own. Russia crushed Eastern Europe under ice-wreathed fists, while Japan and Korea clashed in naval wars where tsunamis of mana-drowned fleets. Blood soaked the earth; cities crumbled under gore-filled sieges where soldiers tore each other apart, limbs ripped by invisible forces, entrails spilling as hearts overloaded with unchecked power.
The wars raged for seven brutal years, claiming billions. Limbs regenerated only to be severed again, screams echoing as mana-fueled regenerators clawed back from the brink, their bodies twisting into grotesque parodies of humanity. Finally, in 2022, the Special Defense Force (SDF) emerged from the ashes—a neutral, elite organization forged by war-weary survivors. Not beholden to any single nation, the SDF operated as a global peacekeeping military, with branches in every major country. Their ranks were ironclad:
Commander: The supreme leader, overseeing all operations with unyielding authority.
Vice Commander: The right hand, handling strategy and internal affairs.
Division Captain: Leaders of specialized divisions (e.g., Assault, Recon, Containment), commanding hundreds in supernatural combat.
Vice Division Captain: Deputies who execute field tactics, often the first into the fray.
Squad Captain: Frontline commanders of small teams, masters of brutal, close-quarters mana warfare.
Squad Vice Captain: Support roles, ensuring squad cohesion amid the gore.
Members: The grunts, honed in powers that could eviscerate foes in seconds.
The SDF brought uneasy peace, quelling uprisings and enforcing mana resource treaties. But beneath the surface, shadows stirred. The "Black Heart" phenomenon—a dark evolution where overwhelming negative emotions shattered the heart's mana limits. It granted godlike power: flames that melted steel, shadows that devoured light, strength to pulverize mountains. But the cost? Insanity. Users became rabid beasts, driven by rage, hatred, or despair, their eyes blackening as veins pulsed with corrupted mana. Governments salivated over it, experimenting in secret labs to weaponize Black Hearts against the SDF, dreaming of subjugating the peacekeepers. Yet every attempt failed; the madness was untamable, leaving trails of slaughtered scientists and mangled test subjects.
In the bustling streets of Neo-Seoul—a rebuilt fusion of old Korea and futuristic spires—lived a boy untouched by the SDF's glory, yet scarred deeper than any battlefield. His name was Min-jun Park, a 17-year-old high schooler with sharp features, messy black hair, and eyes that hid storms. He wasn't alone; he had his father, a weary mechanic named Tae-hoon Park, who drowned his grief in oil-stained workshops, and two younger siblings: 12-year-old Ji-yeon, a bubbly girl with budding mana sparks that lit up rooms, and 10-year-old Dong-woo, quiet and watchful, his powers still dormant.
Their mother, Soo-jin, had been the light of their world—until that rainy night eight years ago. Min-jun remembered it in vivid, nightmarish flashes. They were huddled in their small apartment when intruders burst in, mana-wielding thugs from a rival cartel fighting over a hidden Mana Vein beneath the city. Soo-jin, a gentle healer with soft water manipulation, stood between them and her family. "Run!" she screamed, waves of liquid shielding them.
But the leader, a hulking man with earth powers, laughed. He slammed a fist into the floor, spikes of rock erupting. One pierced her chest, blood spraying in a crimson arc as she gasped. Min-jun, only nine, froze as another thug grabbed her, forcing her to watch her children's terror. "This is what happens when you hide Veins," the man snarled, then crushed her heart with a mana-infused grip. Her body convulsed, mana leaking like black ichor, her eyes glazing over in agony. Gore splattered the walls—flesh torn, bones cracking—as the siblings screamed. Tae-hoon arrived too late, blasting the intruders with raw force, but Soo-jin was gone, her lifeless form crumpling in a pool of her own blood and shattered dreams.
That trauma etched itself into Min-jun's soul. In the aftermath, as grief consumed him, his heart... shifted. Rage boiled, and for the first time, he felt the Black Heart awaken—not as madness, but as a switch he could control. Power surged, shadows coiling around him like vengeful serpents, but he reined it in, flipping back to normal before insanity took hold. No one knew; he buried it deep, fearing the governments' hunters or the SDF's scrutiny.
Now, in 2025, Min-jun navigated high school like any teen, but whispers of unrest grew. Rumors of a new cartel experimenting with forced Black Heart awakenings. And then there was her—Aiko Tanaka, the transfer student from Japan, with piercing green eyes and wind powers that made her untouchable. She sat next to him in class, her smile hiding secrets, sparking something in his guarded heart. Little did he know, their paths would collide in blood and fire, testing his dual-hearted curse.
As the school bell rang, Min-jun slung his bag over his shoulder, ignoring the ache in his chest. But outside, in the shadowed alley, a group of mana-thugs cornered a girl—Ji-yeon. "Hand over the kid; she's got potential," one growled, flames licking his palms.
Min-jun's eyes darkened. The switch flipped. Black Heart engaged.
The air thickened with shadows, tendrils lashing out. The first thug screamed as a shadow blade sliced through his arm, blood fountaining in a gory spray, limb hitting the ground with a wet thud. Another charged, but Min-jun's enhanced speed blurred him forward, fist punching through the man's gut, entrails spilling like uncoiled ropes. Gore painted the walls, the metallic tang filling the air as Ji-yeon whimpered.
He flipped back, heart normalizing, sanity intact. But as the survivors fled, Min-jun realized: This was no random attack. The cartels were hunting families like his—trauma-scarred, Black Heart prone.
What fate awaited him? Peacekeeper or monster? Only time—and blood—would tell.