Ren Kisaragi learned two rules before he learned how to read.
First: In this city, promises were currency.
Second: Every promise had a price.
Rain turned the cobblestones into black glass as Ren slipped through the alleyways of Kurogane District, cloak hugging his shoulders like a second shadow. The lanterns were dying one by one, their light swallowed by fog and the smell of iron.
Somewhere behind him, boots hit puddles—too steady, too disciplined.
Guild men.
Ren didn't look back. Looking back was how you died.
He pressed a hand to the inner pocket of his coat. The leather sat there like a heartbeat that didn't belong to him—warm, heavy, wrong.
The Name Ledger.
A forbidden artifact, rumored to be older than the Kingdom's first throne, older than the first vow ever written. Ren hadn't believed in rumors until three hours ago, when he saw ink move on its own like it was breathing.
Now he believed in one thing only:
If he got caught, they wouldn't just kill him.
They'd erase him.
Ren cut left into a narrower passage where the buildings leaned close enough to touch. A ragged sign swung overhead—OATH-BROKERS, TENTH FLOOR—its letters half-peeled like a dead tongue. Above, balconies dripped rainwater, and distant thunder rolled like an argument between gods.
The boots behind him accelerated.
Ren swore under his breath and pulled a coin from his sleeve.
Not silver.
Not gold.
A vow-coin: dark glass with a hairline crack through its center. Inside the crack, a pale word flickered—STAY.
Ren's thumb traced the edge.
The coin warmed.
The alley listened.
He flicked it forward.
"Stay," Ren whispered.
The word left his mouth with a bite, and the city answered.
The rain stopped falling in the space of a breath.
Not everywhere—just in a thin line ahead of him, like an invisible wall had been drawn across the passage. The puddles held perfectly still. The fog froze mid-curl.
The Oath took.
Ren sprinted through the silence.
Behind him, the first pursuer hit the line.
His foot landed in the wrong world.
For a single heartbeat, the man was stuck—ankle deep in air that refused to move. His balance broke. He stumbled with a strangled curse.
Ren didn't smile. Magic never came for free.
He felt the Oath Tax immediately.
A sharp, cold tug behind his eyes, like someone plucked a thread from his skull.
Ren blinked.
And for half a second, he couldn't remember his mother's face.
The memory returned in fragments—dark hair, tired hands, a lullaby without words. But the edges were already fraying.
Ren's jaw tightened. "Damn it."
He ran harder.
A second sound joined the chase: a low, ticking hum, like a clock buried in stone.
Ren's stomach sank.
Collectors.
Only the Collectors used vow-engines.
He vaulted a stack of crates and slid under a rusted staircase. At the end of the passage, a door waited—cheap wood, fresh lock, no sign.
Safehouse.
Ren had never seen it before. Which meant it was either salvation or bait.
The ticking grew louder.
Ren pushed the door open—
—and stepped into candlelight.
A small room. Clean. Too clean.
Shelves of sealed scrolls lined the walls, each wrapped in white string. An iron basin sat on a table beside a blade so thin it looked like it belonged to a surgeon.
And behind the table stood a girl in a dark kimono, sleeves tied back, her black hair pinned with a silver paperclip shaped like a crescent moon.
Tsukino Aoi.
Ren knew her name the way every criminal knew it—spoken in whispers, written in warnings.
He froze with the Ledger still pressed to his ribs.
Aoi's eyes lifted to his.
Cold. Precise. Unafraid.
"You're late," she said.
Ren's grip tightened. "Do I know you?"
"No." She nodded at his coat. "But you stole something that belongs to me."
Ren swallowed. "It doesn't belong to anyone."
Aoi's gaze sharpened, as if he'd insulted her personally. "Everything belongs to someone. Especially vows."
Outside, the alley filled with shadows. Men in hooded coats. Steel glints. A vow-engine's ticking like teeth.
Ren shifted his weight, ready to bolt.
Aoi raised one hand, palm up, calm as a priest at a funeral. "If you run, they'll take your name. If you fight, the Oath Tax will take what's left of you."
Ren's pulse hammered.
"Then what do you want?" he asked.
Aoi stepped closer. Close enough that Ren smelled ink on her skin, clean and sharp. She reached out—not to touch him, but to touch the air between them.
The candles flickered.
The room went silent.
Aoi's fingertip hovered over Ren's coat pocket, over the Ledger.
"Open it," she whispered.
Ren's throat went dry. "I can't. I tried."
Aoi's lips curved—not a smile, not quite. "You tried alone."
She took his wrist.
Her skin was warm.
The moment she touched him, the Ledger pulsed like a living heart.
Ren's breath caught.
Black ink bled through his sleeve, crawling over his wrist in thin lines—circling, branching, forming characters he didn't know how to read but somehow understood.
A mark.
An oathmark.
Aoi's wrist lit with the same mark.
Her eyes widened for the first time.
Outside, the door shuddered as something heavy hit it.
Ren stared at their matching marks, mouth barely able to form words.
"What did you just do?" he breathed.
Aoi didn't answer.
She listened to the pounding, to the ticking, to the city closing in.
Then she looked at Ren like he was a blade she'd just unsheathed.
"We just made a vow," she said softly.
Ren felt the Tax already—something slipping, tearing, being taken.
His own name on the tip of his tongue suddenly tasted unfamiliar.
Aoi's voice cut through the panic.
"Repeat after me," she ordered.
The door cracked.
"And don't get the words wrong," Aoi added, eyes bright with fear she refused to show.
"Because if you do…"
The oathmark burned.
Ren's vision whitewashed.
"…the Ledger will collect you first."