1994, Fuyuki City.
This coastal city always seemed to be shrouded in an inescapable haze, making the early spring sea breeze carry a damp chill that sent shivers down one's spine.
The neon signs of Shinto's bustling streets flickered. For ordinary high school students, the time after school belonged to freedom and revelry.
"Sumire! Over here, over here! Hurry up!"
At the entrance of a large arcade, several girls in sailor uniforms waved excitedly.
"Coming, don't rush me."
The girl named Sumire smiled helplessly and quickly caught up.
Her name was Sumire Kamado, an ordinary first-year high school student at Fuyuki City's Homurahara Academy.
The young girl had smooth black hair with natural dark red tips. In her clear, bright eyes, a warm luster akin to rubies flowed.
There was a faint red birthmark on the left side of her forehead, which she usually kept hidden beneath her bangs.
Despite her delicate and cute appearance, Sumire Kamado was a famous physical powerhouse at school.
Whether it was long-distance running, the high jump, or kendo, she easily took first place, effortlessly outmatching even the boys in various sports clubs.
"Hey, hey, Sumire, do you want to try that newest fighting game today?"
"I heard Tanaka from the next class lost several thousand yen on that machine yesterday!"
Her companions chattered away, pulling Sumire into the noisy arcade.
Electronic sound effects, the clinking of coins, and the cheers of youths mixed together, forming the unique clamor of high school life.
Sumire skillfully sat down at an arcade cabinet, rolling up her sleeves to reveal her fair yet toned forearms.
As the coin was inserted, the letters "K.O." flashed continuously on the screen.
Challenger after challenger was defeated by her, and unknowingly, a growing crowd gathered to watch.
"So amazing! Sumire is completely invincible!"
"Her reaction speed is way too fast, I can't even see her inputs!"
Amidst the chorus of praise, Sumire merely smiled modestly and picked up her schoolbag resting nearby. "It's just good luck. Um... I should probably head back now. Someone is waiting for me at home for dinner."
"Eh? You're leaving so early?"
"If I go back late, my mom will worry," Sumire said, scratching her cheek with a gentle gleam in her eyes.
Bidding farewell to her reluctant classmates, Sumire walked out of the arcade alone.
The sky outside had completely darkened.
Night in Fuyuki City seemed to fall earlier and heavier than in other cities.
Walking on her way home, Sumire subconsciously reached into the side pocket of her schoolbag and touched a hard, wooden object.
It was a wood carving of a butterfly resting on a leaf.
Although the carving technique seemed a bit rough and it couldn't be considered a fine piece of art, the surface of the wooden butterfly had developed a warm, smooth patina from years of being handled.
But this was the Kamado family's heirloom.
According to her grandfather, his father had received it from a benefactor named Asuka, who had carved it with his own hands.
It was said that the benefactor was a one-armed swordsman who carved this little trinket to comfort his blind wife.
For some reason, Sumire had loved this wood carving since she was a child.
Whenever she held this wooden butterfly, a warm current seemed to surge through her body.
It was a wondrous feeling... her five senses would become exceptionally sharp, even allowing her to perceive the 'flow' in the air that ordinary people could not see.
Her grandfather said this was because a power known as Breathing flowed within the Kamado family's ancestral martial arts.
And because this wood carving retained the powerful energy of that benefactor, wearing it year after year sharpened the breathing perception of the Kamado descendants, which was why it had been passed down through the generations.
"Huu..."
Sumire took a deep breath.
The air was slightly chilly, but after entering her lungs, it transformed into searing energy that flowed through her body along with her blood, making her feel much lighter.
"I need to hurry back, or I'll miss the Slam Dunk rerun..." she muttered.
At an intersection, her footsteps faltered.
A sudden sense of unease crept up from behind, causing her to whip her head around and stare warily into the pitch-black alleyway.
There was no one there, only a few stray cats rummaging for food by the trash cans.
'Is it my imagination...'
She frowned. That prickling sensation of being watched didn't disappear; instead, it grew stronger.
She needed to get home quickly.
Sumire quickened her pace.
But when she turned her head again, a pair of rough, large hands suddenly reached out from a blind spot she hadn't noticed.
"Who is it?!"
Sumire's reaction was incredibly fast. Almost the instant the assailant made a move, her body instinctively dodged.
If it were an ordinary thug, they definitely wouldn't have been able to grab her.
But the moment she dodged sideways, a mist reeking of chemicals was sprayed directly into her face.
It was highly concentrated ether, mixed with some kind of neurotoxin.
"Ugh..."
Sumire instantly felt her brain become as heavy as lead, and the breathing rhythm she had just established was immediately thrown into chaos.
Her limbs went weak, and her vision blurred.
In the final second before her consciousness plunged into darkness, she saw the face of a young man with a cheerful smile but hollow eyes.
"What great luck, I picked up a fantastic piece of material," the man said, as casually as if he had found a pretty soda can on the side of the road.
Drip.
Drop.
The sound of cold water dripping awakened her slumbering consciousness.
Sumire struggled to open her eyes, a splitting headache forcing a muffled groan from her lips.
What greeted her sight was not her familiar ceiling, but a dim, damp, and moldy unfinished concrete wall.
This place seemed to be a basement or some abandoned sewer facility.
A nauseating stench permeated the air.
It was the smell of rust, and also... the stench of blood!
Sumire jolted awake and tried to sit up, only to find her hands and feet tightly bound by rough hemp rope, securing her to a rusty iron chair.
She looked around, her pupils instantly shrinking to the size of pinpricks.
The room was massive, the floor covered with a thick layer of plastic sheeting.
And on that plastic sheeting lay several silent figures.
There were males and females, all appearing quite young, still wearing the uniforms of various schools.
The boy closest to her had a deathly pale face, bulging eyes, and a gruesome gash across his neck.
The blood had already coagulated into a dark brown crust, indicating he had been dead for quite some time.
The other bodies were in similar states.
In the corner, two girls were huddled together, shivering uncontrollably. They had cloth gagging their mouths, their eyes filled with absolute despair and terror.
'Where... where is this...'
Sumire forced herself to calm down.
She couldn't panic.
She silently recited her grandfather's teachings in her heart.
No matter how desperate the situation, she had to maintain a steady breathing rhythm.
'Total Concentration...'
Although her lungs still burned from the residual drugs, as she adjusted to her unique breathing rhythm, the heart-pounding terror was forcefully suppressed.
Her senses began to extend outward.
In the center of the room, a massive, eerie magic circle was drawn in fresh blood.
The lines of the circle were twisted and maddening, exuding an ominous aura that blasphemed life itself.
Standing beside the magic circle was a young man in a purple shirt.
He had messy, short brown hair and wore the harmless smile of a cheerful college student you could find anywhere.
"Are you awake? That was fast, your constitution is really something."
The man's lighthearted voice drifted over.
"Let me introduce myself. I'm Ryunosuke Uryu. It's a pleasure to meet you."