School District 10.
Today was supposed to be a bright, sunny day, but Accelerator's mood was anything but pleasant.
Not long ago, Accelerator had been invited to participate in the Level 6 Shift Project. Without realizing it, he had killed Misaka Sister No. 1. By now, he had already lost count of how many identical clones he had slaughtered.
He felt lost. Despite a week of continuous killing, his strength hadn't increased much at all. For someone who craved power, this was unbearable.
He couldn't help but think of Kakine Teitoku. Rumor had it that Kakine had once fought the Number One—though he had been beaten half to death, his ability had improved tremendously afterward. During later ability tests, his scores skyrocketed.
That made Accelerator realize something—the true essence of the Level 6 Shift Project was probably for him to fight other Level 5s to evolve further. But since the clones couldn't match the strength of the original, he had to kill 20,000 Sisters to achieve absolute power.
The thought disgusted him. Killing weak clones was meaningless. If he wanted to fight, he wanted to fight someone strong.
Once that thought took root, it refused to leave his mind. "The Number One, huh...?"
...
At that moment, Selene had no idea that she had caught Accelerator's attention.
She was currently visiting Nagatenjouki Academy in School District 18—the longtime rival of Tokiwadai Middle School.
Nagatenjouki Academy was also one of Academy City's five elite schools. Unlike Tokiwadai, which focused solely on ability development, Nagatenjouki also valued students' non-ability talents during admissions. In the canon timeline, the school had twice defeated Tokiwadai during the Daihasei Festival to win the overall championship. Many of its researchers had once participated in the Level 6 Shift Project and maintained deep ties with both the Board of Directors and the Dark Side.
Moreover, School District 18 wasn't just home to Nagatenjouki—it was a major hub for other scientific research schools and served as the greatest rival to the School Garden, housing a large concentration of scientists and researchers.
Due to several new projects being launched, the Schicksal Research Institute urgently needed more researchers, so naturally, they had turned their sights toward School District 18.
Shuji Matsuzaki, who was in charge of recruitment, had been working himself to exhaustion to fill the shortage. Besides standard corporate and campus hiring, he had been "digging corners" everywhere he could—with generous financial backing from Selene.
This time, Selene had come along, not for any business purpose, but simply out of curiosity—to see for herself the unique educational philosophy of Tokiwadai's old rival.
As night fell, Selene sat on a park bench by the riverside, relaxing after a long day.
"Hey, Number One—fight me."
A raspy male voice suddenly emerged from the darkness.
Selene looked up toward the source. A shadowy figure slowly stepped into the light—a young man with white hair, red eyes, and a lean frame. His black T-shirt with white patterns gave him a delinquent air, and the madness in his expression was palpable.
"Number Two... Accelerator?"
The boy tilted his head slightly, a twisted smile forming on his face as he stared at the silver-haired girl before him. "Fight me."
Before Selene could respond, Accelerator raised his foot and lightly tapped the ground.
Boom!
A thunderous shockwave burst out from beneath him, rippling outward at visible speed. The park's ground cracked apart, the grass, flowerbeds, and trees all shattering as clouds of dust rose into the air.
"Is this battle sanctioned by the Academy?" Selene asked calmly as she stepped unscathed from the dust cloud.
"Hahaha—hahaha! You're strong, just as I thought!" Accelerator laughed maniacally and launched another attack.
With a loud crash, the ground beneath Selene split open and collapsed.
"Are you sure you want to do this?" Selene's tone hardened. Being attacked without retaliation wasn't her style—and she was already in a foul mood.
From the smoke, chunks of rebar and debris shot toward her, their paths warped by Vector Manipulation.
Seeing Accelerator's decision, Selene no longer hesitated. A pitch-black void swallowed the incoming projectiles, and in the next instant, they were hurled back through spatial acceleration.
With a metallic clang and a burst of sparks, the rebars disintegrated into dust against Accelerator's reflection barrier.
Accompanied by manic laughter, Accelerator's attacks grew even more violent. The entire park was completely destroyed—the ground cracked inch by inch, chunks of cement mixed with dirt and grass were hurled toward Selene.
But under Selene's spatial ability, every single attack was reflected back through her dimensional portals.
At this point, neither Selene nor Accelerator could gain the upper hand.
Logically speaking, Dark Matter was even more troublesome than Vector Manipulation. Vector Manipulation, at least, followed some kind of mathematical logic. But Dark Matter—that was something created from nothing.
Dark Matter allowed the user to generate and control particles that did not originally exist in this world and alter their physical properties at will.
The fact that Accelerator could overpower Kakine Teitoku wasn't just because of his Vector Manipulation. His strength came from himself—his brain's calculation capacity was terrifying beyond belief.
"Interesting! This night's getting fun!" Accelerator's excitement grew. He seemed to have rediscovered the thrill of battle.
For some reason, Selene's mood, however, darkened. A crimson flash crossed her eyes.
The violent aura inside her began to surge.
Swish!
"What the—!" A pitch-black ribbon suddenly appeared out of thin air, cracking through the air like a whip toward Accelerator. The sound of it slicing the atmosphere made his pupils contract.
BOOM!
A deafening explosion followed. The ground beneath Accelerator burst open, soil blasting skyward like a torrential downpour of rock and dirt—a rain of sand and stone.
Though his skin-reflection ability remained intact, the immense force sent Accelerator flying through the air, slamming straight into the nearby river bridge.
Crash!!!
Concrete and rebar scattered as the bridge snapped in half and collapsed instantly.
Amid the rubble, Accelerator clutched his head, standing shakily on the water's surface with the aid of his reflected vectors.
Before he could catch his breath, BOOM!—Selene descended like a meteor, wrapped in lightning, crashing down in front of him. The sheer force pulverized the nearby bridge pylons, and the surrounding river water instantly vaporized.
BOOM!!!
Before the steam had even dispersed, an immense repulsive wave burst forth. The receding river water was blasted back again. Fueled by Selene's anger, the resulting explosion was far greater than before. The roaring sound drowned out everything, erasing all traces of the bridge. The embankments on both sides shattered instantly.
The ground quaked violently. Buildings along the riverbanks trembled madly, houses crumbled, street trees were uprooted. Within several kilometers, the earth heaved like rolling waves, making it impossible to stand.
The entire Academy City seemed to awaken to the thunderous blast.
As the smoke rose skyward, the riverbed was transformed into a kilometer-wide crater where no grass grew.
"Cough... cough..." Accelerator now knelt at the bottom of the pit, blood flowing from his seven orifices. His eyes were bloodshot, his breathing ragged and wheezing, as if his brain's calculation power had finally hit its limit.
Crackle...!
Blue lightning danced along Selene's skin, flickering with violent energy. The air exploded with every step she took. Her eyes shone bright azure as she slowly walked toward him.
"Your calculation power's reached its limit, hasn't it?"
Selene's voice was flat. Then she raised her foot, wreathed in lightning, and struck.
BOOM!
A blinding flash of blue light engulfed Accelerator's vision, swallowing the entire area. The explosion that followed shook the crater.
"Ugh—!" Blood spurted from his mouth as Accelerator was slammed deep into a rock wall formed by the high pressure.
He groaned in agony. But before he could recover, Selene's second strike arrived.
A black crescent slash tore through the air, whistling with a sharp, mournful sound. The terrifying blade of compressed space sliced through the atmosphere itself.
Slash! Accelerator's overloaded reflection failed. His arm was severed cleanly, the cut extending in a straight line nearly a hundred meters forward. Before he could scream—
Selene appeared in front of him, seized his head, and slammed it repeatedly into the ground. Over and over, the sound of impact echoed, blood spreading across the shattered stones.
At that moment, Kihara Amata, who had been watching from the shadows, sighed deeply and finally stepped forward, speaking with forced composure. "Miss Selene, please stop. You can't kill him—at least, not yet."
Though Kihara Amata was terrified she might kill him next, Accelerator was still the key subject of the Level 6 Shift Project. Under Aleister's orders, he had no choice but to intervene.
Hearing that, Selene tossed Accelerator aside. With a snap of her fingers, a Subspace Lance materialized and impaled him straight into the ground.
Feeling the weight of Selene's killing intent, Kihara Amata froze, not daring to avert his eyes.
"All damages will be covered by Accelerator, and the Board of Directors will ensure your compensation..."
Selene's murderous aura made him take two steps back. The leader of the Dark Side unit Hound Dog looked almost servile at this moment.
Selene's hands and face were stained with blood. Nearby lay the "victim" pinned to the ground. To any outsider, she would appear the villain—a merciless tyrant bullying the weak.
"Fine. But the compensation had better satisfy me. Otherwise..."
With a flick of her wrist, five crescent-shaped slashes carved new trenches before Kihara Amata, and then—Selene vanished.
Seeing her disappear, and noticing the black lance impaling Accelerator fade away, Kihara Amata exhaled in relief.
"What are you waiting for? Get him out of here and start treatment immediately. Don't forget the severed arm—it might still be reattached."
Glancing at the detached limb, he frowned. "That's strange. Last time, Kakine Teitoku's arm was completely vaporized. But this time... it's still intact. Did she hold back?"
As the helicopter ascended, Kihara Amata looked down at the kilometer-wide crater and muttered in awe, "No matter how you look at it... she's terrifying. Is she even human...?"
"From now on," he said coldly, "Hound Dog is forbidden from provoking the Number One."