The city was a constant hum, a symphony of traffic, chattering crowds, and the distant wail of sirens. For Okotsu Yuta, it was just noise, a backdrop to the quiet rhythm of his own extraordinary existence. He moved through the throngs of Shibuya, a seemingly ordinary high school student with an unremarkable uniform and a perpetually thoughtful expression. No one would ever guess that beneath that placid facade lay a mind that could dissect complex physics problems with the casual ease of tying a shoelace, or that his body was a living paradox, a sponge for the very forces that ripped others apart.
Yuta remembered the exact moment his world fractured. It wasn't a dramatic lightning strike or a cryptic prophecy. It was a Tuesday. A Tuesday filled with the usual drudgery of algebra and passive-aggressive homeroom teachers. Then, the screams started. Not the distant, everyday screams of the city, but guttural, inhuman roars that tore through the urban fabric. People, ordinary people, began to twist and contort, their limbs elongating, their skin cracking, their eyes burning with an unholy red glow. Demons. That's what they were called. Or, more accurately, what they became.
Panic erupted, a chaotic wave that swept through the streets. Yuta, oddly calm even then, found himself in the path of a monstrosity that had once been a salaryman. It lunged, a clawed hand tearing through the air, aimed directly at his chest. He braced himself, not out of fear, but curiosity. There was no pain. No impact. The blow landed, hard enough to shatter concrete, but Yuta merely felt a strange thrum beneath his skin, a vibration, a warmth spreading through his limbs. The demon reeled back, confused, its attack absorbed, its kinetic energy siphoned away into an unseen reservoir within Yuta.
That was the first time he truly understood. He could absorb kinetic energy, rendering himself immune to physical harm. And in that same terrifying, exhilarating moment, he also discovered the release. With a thought, the accumulated force surged from his palm, a concussive wave that sent the demon careening into a lamppost, disintegrating into black dust upon impact.
Since then, the world had become a battleground. The city, outwardly normal, was a thin veil over a horrifying reality. The hidden underworld was no longer hidden; it was spilling out onto the streets, one random transformation at a time. Every day, someone new, someone innocent, became a monster, driven by an insatiable hunger to kill.
Yuta had made it his solitary mission to eliminate all the demons. He wasn't a hero. He didn't crave glory. He was a genius who saw a problem, and this problem, this blight of humanity turning into ravenous beasts, was one he was uniquely equipped to solve. He stalked the shadows of alleyways, listened for the tell-tale growls beneath the city's hum, and waited.
Tonight, the hum was off-key. A subtle dissonance beneath the usual urban cacophony. It was the sound of something tearing, something wrong. Yuta veered off his usual path home, his senses sharpened, honed by countless encounters. He knew that sound. It was the precursor. The city was bleeding again.
A piercing scream echoed from a nearby izakaya, followed by a chorus of terrified shouts. Yuta broke into a run, his steps light, almost imperceptible. He rounded the corner, the neon glow of the restaurant sign painting a gruesome tableau. Inside, tables were overturned, shattered sake bottles glinted on the floor, and a hulking figure, its skin like cracked asphalt and its eyes glowing crimson, was tearing through the patrons.
It was a fresh one, just turned. Bigger than most, fueled by the kinetic chaos of its transformation. It snarled, its gaze locking onto Yuta. A new hunter had entered its territory. And Yuta, calm and collected as ever, knew he was about to provide it with a very, very painful lesson in applied physics.