Prologue: Radio Noise.

The wind blew powerfully. Dusk had set in while a lone girl, sprawled on the roof of a building to conceal her body, squinted slightly. She was equipped with a rifle that was ridiculously large for her size, a length of 184 centimeters that easily surpassed her height.

The Metal Eater MX. It was a Barrett M82A1 anti-tank rifle that was legendary for having destroyed a tank from 2,000 meters away during the Gulf War. Production models lacked fully automatic firing because of the excessively powerful recoil, but the gun she held was a prototype model that retained the rapid-fire setting.

Though it was a brutal rifle capable of crushing a cheap helmet into pieces with simply the recoil, the slender girl seemed accustomed to wielding it. For someone with her physique it was impossible to forcibly suppress the recoil so the kickback had to be forcibly diverted into the ground. But rather than years or practice, the girls simply had fourteen days of data inputted via the training equipment known as Testament. Upon completion, she had learned the Metal Eater's recoil strength and had derived the calculations necessary to compensate the recoil with optimum efficiency.

Silencing her breathing, the girl gazed at her 600-meter away "target" through the cold scope.

Insects gathered underneath a convenience store light while a fifteen or sixteen year old boy walked out onto the street. His physique was thin and wiry and his hair as white as the girl's delicate skin. He looked like he would snap if a person grabbed him.

However, he would have been better described as the sharp point of a knife. Each and every one of the boy's official battles recorded in the databases was a victory. Even more, he had never been hurt, never defended himself, and never evaded—not a single time. The boy was like a thin and fragile but highly polished saber designed exclusively for offense without a consideration for defense.

Although the girl knew not her target's true name, his code name was Accelerator. Within Academy City, there were only seven individuals ranked Level 5 and, even within that list, the boy's name stood at the very top.

The crosswinds are strong... Correcting alignment three clicks to the left. The girl muttered under her breath while she turned a screw on the side of the rifle's scope. The girl's target was the boy swinging his convenience store bag with boredom on his way home. She was surely unable to defeat him by opposing him head on—no one could possibly have defeated Accelerator without an underhanded method.

If head on were impossible, she would not do so. For espers, using their abilities was like moving their limbs. Aside from Level 0s that lacked any significant power, the structures of powers were roughly classified into two categories: active and passive. Active powers were abilities that the users deliberately controlled while passive ones activated reflexively as the user sensed danger. Thus, if a surprise attack connected before the enemy noticed he was in danger, any sort of ability user was defeated.

Academy City's Judgment had once implemented the tactic by firing rubber bullets from a distance in order to stop rampaging ability users. However, those rubber bullets knocked people unconscious while the girl was ending a life with steel, piercing ammunition.

Wind eddies... vortices from three directions. Correcting alignment one click to the right, the girl muttered quietly as she further fine-tuned the scope. Without corrections, the lead bullets would have swerved off target by unexpected winds. Furthermore, considering the city was plagued with buildings, the wind did not per say blow in one direction. Wind eddies, flowing from various directions, collided together and formed vortices dispersing wind in every direction.

To miss was not an option. Her opponent was the strongest Level 5 and if she were detected after her initiative missed, her defeat at that point would have been certain regardless of the distance between them or how far she fled.

The girl placed her finger to the trigger.

She had no hesitation. Despite the fact that the target before her was a living human boy and with the pull a trigger a.50 caliber anti-tank bullet would fire from the rifle at a sky-ripping velocity of 3070 kilometers per hour (852.8 m/s). Though she knew that the boy's upper body would have morphed into shreds of flesh at a speed faster than sound itself, she held no hesitation.

Imposed upon those slender shoulders was but one task: annihilate the strongest Level 5 esper, Accelerator, by sniping him.

"..."

She listened to sounds of the wind as they flowed and swirled into colliding vortexes that formed fixed directions for only moments at a time. For a time period lasting less than two seconds, the complex wind eddies stabilized. She pulled the trigger.

A thunderous roar ripped through the sky like the explosion of a fireworks factory. Despite the fact that she was sniping, the girl continued to fire on full-automatic. She tenaciously absorbed the recoil capable of toppling over large adults and, within a single second, twelve shots were fired with consistently pinpoint accuracy.

The ignored her emptied magazine and observed the fate of the boy through the scope. Since the wind flows were stable, it was impossible to miss. All twelve bullets would pierce the boy's back; that slender, wire-like physique would shatter and burst into tiny chunks.

That should have been the case. But, the next instant, the Metal Eater in the girl's hands exploded. The rounds that connected directly... rebounded. Almost like a video playing in reverse, the shells' ballistics redirected, plunging perfectly back into the muzzle of the anti-tank rifle like a Kendama game, bursting the Metal Eater into tiny fragments.

The girl lacked the visual acuity to detect the incoming bullets. The extent of her knowledge ended at the fact that the rifle way destroyed by some impact. Her body was pierced by the countless fragments of metal while her right shoulder, which was pressed against the Metal Eater's stock, was severed by something passing through it. Somehow, Accelerator himself, after taking the rifle's shots, was unharmed. In the end, the sniping had failed; Accelerator had detected it. That fact alone was enough for the girl to make her next decision. The girl, with her tattered body, ignored her intense pain that felt like boiling water was poured over her head as she fled toward the building's flight of emergency stairs.

In that moment of time where the firing failed, the girl had lost her 1-in-10,000 chance of victory. Thus, her retreat, rather than to reassess the situation, was her only course of action to prolong her lifespan by a moment, a second.

The reverberation of footsteps was absent in the dusk. The hunter closed the distance between himself and the dying girl with total silence. The hunter versus the hunted... The curtain was raised for a murder drama where the two roles were reversible in moments.