The wind howled across the open sea as Ark-09 descended through the storm clouds, cloaking itself in silence. Beneath them lay the hidden outpost: Abyssus Sanctum, an underwater cathedral built by the Ministry during the Old Wars.
"It used to be a place of refuge," Eva said over the comms. "Now, it's gone dark. No communication. Last intel said a Vatican envoy was sent there two days before it blacked out."
Daiki frowned, sitting cross-legged, eyes shut.
"There's a fog here... too much blood, too many secrets."
"It's not fog," Haru muttered, checking his ammo. "It's memory."
"What do you mean?" Ren asked.
Haru glanced at them, half a grin on his face but no joy in his eyes.
"My father died down there."
Silence.
Even Icarus froze for a moment.
The sea churned below. Thunder cracked overhead. And the Abyssus Sanctum opened its mouth.
Descent Into the Dead
The team entered through the emergency shaft, air tight and rusted shut from disuse. The moment they breached the outer gate, the lights flickered on—not with warmth, but cold precision.
The halls were pristine. Too pristine.
Not a drop of blood. Not a body. Just silence.
"It's like they all vanished," Ren said, sword in hand.
"No," Icarus muttered, placing a hand on the wall. "They were consumed."
As if in answer, a sudden screech rang out—mechanical, ancient, inhuman. The lights flickered red. Then a voice—a child's voice—whispered from the ceiling:
"You've come to bury the past… or be buried with it?"
The floor beneath Daiki cracked. He leapt, barely dodging a spiked vine made of blood-forged cables.
"What the hell?!"
From the shadows came the enemy.
Not demons. Not soldiers.
Monks.
Former Ministry monks—stitched together with wire and blessed chains, half-machine, half-demon. Their faces hidden beneath broken scripture masks.
"They were turned," Haru said, his voice low. "That's why no one answered. They weren't killed… they were converted."
Trial of the Sanctum
The boys fought through the cathedral, every hallway twisted with Vatican tech repurposed for demonic rituals.
Ren slashed through four monks in a burst of wind, his blade dancing like a whisper. Daiki used foresight to predict the trap doors and glyph traps before they activated. Haru burned through ambushes, his fire muffled by the flooded corridors.
But it was Icarus who saw the truth first.
A mural.
In the Sanctum's Grand Hall, hidden beneath a layer of rust and ash.
It showed four boys—dressed like kings, fighting titanic beasts of shadow. At their backs, a fifth figure, faceless, with a bleeding crown.
Beneath it, in forgotten tongue, read:
"The Four Will Burn the Seal. And The Fifth Will Rise."
Icarus's expression darkened.
"There's more to this than demons."
The Betrayal
At the Sanctum's heart, they found it—a throne of bones, floating above a pool of corrupted mana. Sitting on it, connected to a dozen tubes, was the Vatican envoy.
Or what was left of him.
His voice came in spurts, warped by cybernetic breathing.
"Welcome, sons of the war… It's time to choose."
He lifted a hand, and the mana in the room shifted. It pulled toward the four.
"Your blood is the last key. The Vatican wants to unlock the seal beneath this sea. To awaken the first sin—Wrath."
Haru's body tensed.
The pool behind the envoy began to glow red, rising.
"One of you already carries the mark."
The group turned—staring at each other.
"What?" Ren said, stunned.
"Liar," Daiki spat. "You're trying to fracture us."
"Am I?" the envoy wheezed. "Then why does he glow?"
He pointed—at Haru.
The flames around Haru were flickering violently. And on his right arm, visible now through torn sleeve, was a strange mark. A sigil shaped like an eye pierced by a sword.
Haru stepped back, stunned.
"No… that's not—That wasn't there before."
"It was sealed," Icarus whispered. "Until now."
Ren stepped between Haru and the envoy.
"He's one of us. We don't abandon family."
"Then die together," the envoy screamed, activating the sanctum's core.
The corrupted mana exploded.
Blood-Sealed Combat
What rose from the pool was not a demon—it was an ancient prototype, created by the Vatican centuries ago and fused with the soul of a high-ranking demon. A Seraphim-class hybrid, known as Red Eidolon.
Ten arms.
Four wings of steel.
A core that pulsed with flame.
The boys didn't hesitate.
Ren unleashed a typhoon slash that severed one wing. Icarus folded space to bind three arms at once. Daiki charted the enemy's movements, directing them through blind spots and forming patterns mid-battle.
And Haru… Haru stood still.
The mark on his arm burned.
"If this thing is feeding off me…" Haru muttered, "then it's my responsibility."
His pistols ignited. Not with fire. But with blue flame—a higher form.
He charged forward, faster than before. Stronger. He screamed through the pain of his awakening, diving into the Eidolon's chest—
And pulled the core out.
The Eidolon let out a soul-wrenching scream before crumbling into ash.
Aftermath: Broken Waters
The Sanctum collapsed behind them.
They emerged through the emergency exit tunnel just before the sea reclaimed it.
On the deck of the Ark, silence hung heavy.
"You knew, didn't you?" Haru asked Icarus.
Icarus didn't answer.
"I don't care," Ren said. "You're still one of us."
"Always," Daiki added. "But we need to find out what that mark means."
Haru looked at the ocean, thoughtful.
"One of us is marked. But maybe more of us are cursed