Beneath Pangea Castle, below the radiant throne room of the so-called gods, there existed a chamber that no light dared enter. Carved into the bones of the Red Line itself, the air within was dense—heavy with salt, sorrow, and the echo of ages long extinguished. This was no mere dungeon. It was a tomb for the divine.
And in that tomb, Poseidon—the Ancient Weapon, the Sea's True Voice—had been chained for nearly a millennium.
The chains that bound her were monstrous things, forged from the spine of the world itself.
Each link was as thick as a tree trunk, blackened by age and pressure, humming faintly with the same power that held the oceans at bay. They pierced deep into the bedrock, binding her essence to the marrow of the Red Line.
Once, Poseidon had sung to the currents and the whales, her laughter carrying across the sea like dawn's first light. Now, her voice was a whisper lost in the darkness. Only Imu knew this place still existed. And lately, they had been visiting far too often.
Their footsteps echoed along the stone causeway—measured, deliberate, almost ritualistic.
But this time, something was different. Imu did not linger to watch the flickering candles or to study the ancient inscriptions that spoke of forgotten gods or even stop near the massive straw hat.
They moved directly toward the far end of the chamber—to the chained goddess herself. Poseidon lifted her head slightly as the intruder entered. The faint shimmer of her scales caught what little light seeped from Imu's torch. Her once-luminous hair hung in pale, tangled waves across her shoulders. Her eyes—eyes that had seen the rise and fall of empires—followed Imu's every step.
Imu's voice broke the silence, calm and chillingly composed.
"The royal line of the fishmen has given birth to a mermaid once more… after nearly two centuries."
They dragged a gloved hand across the stone altar that lined the prison wall, brushing past the withered husks of small mermaids—children who had been brought here long ago. Their delicate bones were entwined in rusted chains, their tiny fins long since turned to dust.
Each one had been royal. Each one had been a potential Poseidon. And each one had been slain before her eyes. Poseidon's gaze dimmed, though her expression did not change. She had wept centuries ago, until there were no tears left to give. Every time Imu had brought another child into this abyss—another innocent life ended in fear of the sea's awakening—something inside her had died with them.
And now, Imu was watching her again, searching for that flicker of recognition. The slightest sign that she knew. But Poseidon had long since mastered stillness.
"Why tell me this?" She murmured, her voice low and resonant, like waves breaking upon a faraway shore. "You are the master of this cage, Imu. If the child is destined to die by your hand, then so be it. This would hardly be the first time you've slain out of fear."
A faint smirk—bitter and worn—tugged at the corner of her lips.
"You call yourself a god… yet tremble before the thought of the sea, remembering its queen."
The silence that followed was suffocating.
Imu's eyes, hidden beneath the faint shadow of their crown, lingered on Poseidon. There was something different in their stare this time—something calculating, something almost human.
Poseidon, however, betrayed nothing. Because she already knew the truth. The new child born beneath the waves was not a possibility. She was the next Poseidon.
And if Imu knew that, they would stop at nothing to snuff her out before the sea could rise again. The chains rattled faintly as a current stirred through the chamber—a whisper of the ocean, seeping through cracks in the world above. And for the briefest of moments, Poseidon's eyes glimmered like the deep.
The chamber trembled as Imu's voice echoed through the hollow heart of the world. The faint glimmer of torchlight danced along the obsidian chains that bound Poseidon, painting the walls in ghostly ripples—like reflections of a sea long forgotten.
For centuries, Imu had visited this prison of gods. Always from a distance. Always in control.
But tonight, something had changed. They stepped closer than ever before—closer than Poseidon thought they dared.
And when Imu spoke, their voice was neither cold nor kind. It was ancient, like a current that had scoured civilizations from the face of the earth.
"Ever since I claimed this world as mine…"
"Over years, decades, centuries—there have been those who dared to challenge my dominion. Brave, perhaps. Foolish, certainly. Yet I triumphed over them all."
Imu's words reverberated like thunder rolling through the ocean's depths. They stopped before the chained goddess, their silhouette small compared to her immense, coiled form. Poseidon's tail shimmered faintly in the gloom—scarred, scales dulled by the erosion of time and pain.
Imu raised a hand and, for the first time in eons, touched her. The contact was almost tender… almost. Poseidon's body shuddered at the sensation. The divine instinct within her screamed that this was wrong—that this being should never touch her. Imu had never before crossed that sacred distance, and yet now their fingers brushed against her wounds with a slow, deliberate caress.
"Do you know what I found most amusing, Queen of the Seas?" Imu murmured, voice soft but dripping with venom.
"What truly made me feel alive?"
Poseidon's gaze hardened. She said nothing.
"It was to watch them—mortals, gods, kings—slaughter their own kin. To see them break themselves for me. Kill, conquer, and betray everything they were, simply to serve my will."
Imu's smile was a ghost—cold and perfect. Their eyes gleamed with a wicked light, unburdened by empathy.
"And now," they continued, "the fishmen have tested my patience again and again. Their arrogance festers beneath the sea, believing themselves safe in your shadow. So tell me, who better than you, their mother, their goddess… to deliver judgment?"
The words struck Poseidon like harpoons through her soul. Her chest constricted, her tail quivered against the chains that held her down.
"You will show them," Imu whispered, leaning close until their breath brushed her ear.
"You will teach your children what it means to defy the God of this World."
Poseidon recoiled, horror flashing across her face for the first time in centuries.
But Imu's hand tightened upon her scales, and a cruel whisper slipped between their lips—ancient, forbidden, and absolute.
"DOMI REVERSI."
The words were not sound but force—pure and terrible. They sank into the marrow of the Red Line, reverberating through every chain, every rune that bound Poseidon's divine essence. Poseidon screamed. The ocean itself seemed to shudder.
The light within her—once radiant as the dawn tide—fractured and bled into shadow.
Her golden eyes clouded to abyssal black, and dark veins of corruption crept across her body like ink spreading through clear water. Her song, once the voice of the sea itself, turned into a low, mournful wail.
She tried to resist. Memories flooded her—children laughing beneath coral spires, whales answering her call, the sea embracing her as its queen. But Imu's power wrapped around her mind like chains of fire. She clawed at her temples, the echoes of her defiance fading with every pulse of that cursed spell.
"No… I am… the sea…" she gasped. "You cannot—"
"You were the sea," Imu corrected softly. "Now, you are mine."
Her body convulsed, scales darkening, her divine aura warping into something monstrous. The chamber filled with a sound like roaring tides mixed with screams. When the transformation ended, the goddess that had once ruled the oceans no longer existed.
Where she once knelt, a demonic Poseidon raised her head—eyes black as trenches, voice a guttural echo of her former grace. Imu regarded their creation with a slow, satisfied breath. The faintest smile crept across their lips—a god savoring victory over another.
"Your first command, my fallen queen…" they said, turning away as the chains dissolved into shadow.
"Destroy your kin. Drown your children. Let the sea remember who rules this world."
And from the depths of that prison, a new tide began to stir—dark and endless—ready to consume all that still dared to dream of freedom.
Far beneath the crushing blue of the ocean, where the sun's light only reached as fractured whispers, Fishman Island glowed brighter than it had in decades.
The gloom that had settled over the coral domes and spiral streets—years of resentment, fear, and hardship—seemed to dissolve overnight. Word had spread like a tidal current: Queen Otohime had given birth to a daughter.
And not just any daughter. A princess.
Among the fishmen, it was more than a royal birth—it was a divine omen. For centuries, the legend held true: whenever a mermaid princess was born to the Ryugu royal family, the seas themselves blessed their kind. Trade flourished, tides gentled, and Fishman Island basked in a rare peace.
And so, for the first time in many weary years, laughter rolled through the coral avenues. The lights of the jellyfish lanterns burned a little brighter. Musicians took to the plazas, their conch-shell horns echoing through the currents. Even the gruffest shark-men found excuses to smile and polish their scales.
Outside Ryugu Palace, the crowds stretched as far as the eye could see—a living tapestry of fins, tails, and shells. Swordfish warriors in polished armor stood shoulder to shoulder with merchants, mothers, and children holding coral flowers. Nobles and commoners alike had set aside pride and prejudice, all drawn by a single uniting purpose: to see the child who would one day be called their Queen.
Inside the palace, the grandeur was overwhelming. The main hall—normally reserved for diplomatic councils—had been transformed into a living coral gallery. Massive seagrass banners fluttered in the currents; pearl chandeliers hung from the domed ceiling, refracting the light into shimmering constellations across the floor.
And at the very center of it all, surrounded by guards, nobles, and family, was a small, glittering cradle carved from a single giant clam shell. Inside it, wrapped in silk spun from golden kelp, slept the reason for all this joy—
Princess Shirahoshi.
Even as an infant, she was breathtaking. Her hair was a pale coral pink, catching the light with every ripple of water. Her tiny fins fluttered now and then, like a butterfly's wings testing the air for the first time. When she yawned, bubbles escaped her lips, drifting upward in lazy spirals.
And standing over her like a fortress carved from stone was none other than King Neptune himself. His trident rested against the cradle's side, but his presence alone was enough to keep even the bravest souls at a cautious distance. His vast frame loomed like a cliff, his mane-like beard flowing with the current, and his eyes—normally kind and full of booming laughter—were narrowed into fierce slits of paternal vigilance.
"Step lightly," he rumbled at a poor courtier who dared lean too close. "That's my daughter you're breathing on."
The unfortunate fishman paled. "O-Of course, Your Majesty! My apologies, I—ah—was only admiring how radiant she—"
"OUT."
The word struck like a cannon blast. The guards—long accustomed to their king's temper—swiftly escorted the offender from the hall.
Queen Otohime, seated gracefully upon a pearl-inlaid chair nearby, sighed softly. Even with the fatigue of childbirth visible in her face, she glowed with serene joy. "Neptune, dear, perhaps you might refrain from tossing every visitor into the current? They've come to bless our child, not lose a tooth."
Neptune crossed his massive arms, frowning. "If they keep pinching her cheeks like she's some coral doll, they'll lose more than a tooth!"
A ripple of laughter passed through the hall, easing the tension. By his side stood the royal sons—Fukaboshi, Ryuboshi, and Manboshi—each positioned like loyal guardians at the four corners of the cradle.
They had inherited their father's size and stubbornness in equal measure. Whenever a visitor bent down to offer their blessing, three pairs of eyes tracked their every movement with almost comical intensity.
"Careful with the fin," Fukaboshi warned one old merman who was trembling with excitement.
"Don't poke her! Don't poke her!" Manboshi added anxiously.
Ryuboshi, always the dramatic one, pressed a hand to his chest. "If you harm a single scale upon her divine brow, I shall never forgive you!"
The poor visitor merely blinked, mumbled a blessing, and scurried off.
Otohime couldn't help but laugh. The sound was soft and melodic, like the tinkling of crystal. "My loves," she said, "perhaps you might allow her to be admired without interrogation?"
Neptune puffed out his chest. "Aye! They may admire her from a distance."
Another round of laughter swept through the court. Despite the king's antics, the atmosphere in the chamber was radiant—like sunlight dancing through clear water. Courtiers and commoners alike came in waves, bowing low and offering gifts: coral carvings, seashell necklaces, pearls as large as fists. Some left small vials of sea foam or tokens of family luck. Others merely pressed a palm to their heart and whispered blessings for peace and prosperity.
But every time someone reached out too far, they met the gaze of either Neptune or one of his sons—and thought better of it.
Outside the palace, the celebration was no less lively. Children were swimming through coral arches, stringing garlands of anemones along the streets. Restaurants were giving away bowls of kelp stew and shell cakes. Musicians lined the coral balconies, playing flutes that sounded like the hum of whales.
Everywhere, laughter. Everywhere, light. Old grudges were forgotten, if only for a day. The merchants who once complained about royal taxes and famine now toasted the king's health. The soldiers who once grumbled about palace politics now stood proud, guarding the gates of joy.
The whole island pulsed with a single heartbeat: hope.
Back in the hall, another brave guest—a manta ray noble with a wide smile—approached the cradle. "Ah, Your Majesty! Might I bless the little one with a traditional coral charm? It brings good fortune and—"
Neptune's eyebrow twitched. "Not too close."
"Of course, of course! Just a small charm, right by her—"
"Too close."
The manta noble froze mid-motion. "Then… perhaps I'll just… leave it on the floor, yes?"
"Wise choice," Neptune muttered, arms still crossed.
The three princes nodded in unison, murmuring their approval. "Father," Ryuboshi whispered, "you have the eyes of a hawkfish."
"I'll have the eyes of a kraken before I let anyone touch her," Neptune grunted.
Otohime chuckled behind her hand. "You're frightening the people, my dear."
"Good. Fear is healthy."
Just then, baby Shirahoshi stirred. A small, squeaky sound—half giggle, half hiccup—escaped her lips as a bubble rose from her mouth and popped against Neptune's nose. The mighty king froze. The entire hall went silent.
Then—slowly, impossibly—Neptune's face melted into a grin. A soft, booming laugh escaped him, shaking the very coral pillars.
"She laughed at me…Jamon!" he roared with pride. "Did you all see that? My daughter thinks I'm funny!"
Fukaboshi, smiling, bowed his head. "Of course, Father. A rare insight indeed."
Ryuboshi added dramatically, "Her taste is impeccable!"
Manboshi clapped his fins. "She's smiling again! Look, she loves us!"
Otohime sighed, though her eyes shone with warmth. "Oh dear… between the four of you, I fear she'll grow up never knowing a moment of peace."
Neptune scooped his daughter gently into his enormous hands, holding her aloft like the most delicate treasure in the sea. His booming voice softened.
"Shirahoshi," he murmured, the name he had chosen himself, refusing all others. "Little pearl of the sea… may the oceans sing your name forever."
As he spoke, the entire hall bowed their heads. The musicians in the corner began to play—a soft, haunting melody that swelled through the chamber like the heartbeat of the ocean itself.
The king turned, raising his daughter toward the light filtering through the coral dome above. The beams struck her tiny form, wrapping her in shimmering radiance. The people gasped, awestruck. For that moment, it truly seemed as if the sea had chosen her—blessing her with the same divine grace once sung of in the old legends.
Outside, the great whale-sharks circling the palace let out low, resonant cries, and the waters of Fishman Island seemed to pulse with life. The currents shimmered gold. The reefs glowed brighter. Even the ancient Sea Kings stirred faintly in the distance, sensing the birth of one who was bound to them.
And amid all this glory, Otohime, weary but smiling, leaned back in her chair. Her eyes found her husband, her sons, her newborn child—and for a moment, she forgot all the hardships, all the struggles, all the shadows that lurked beyond their paradise. For this single day, beneath the weight of the world above, Fishman Island was happy.
The grand coral gates of Ryugu Palace loomed like a living cathedral of the sea, their polished shells glimmering beneath streams of bioluminescent light. The celebration inside had spilled outward; the currents themselves seemed to hum with the laughter and songs of the gathered multitude.
Thousands of fishmen and merfolk wound their way along the palace causeway—a line so long it disappeared into the hazy distance, where the coral streets twisted through the glowing domes of Fishman Island. Each one came bearing a gift.
A token. A fragment of hope.
Some carried flowers woven from seaweed, others bore polished shells, pearls, or toys crafted from drift coral. None of them had much, but all brought something. And for once, the palace guards did not measure worth by wealth or bloodline. Each citizen, from noble to beggar, was permitted to step through the palace gates and pay homage to the newborn princess. It was a sight that had not graced Fishman Island in generations.
"Oye! Stop shoving!"
The irritated cry came from a horsehead fishman, his long snout flaring as he stumbled forward, balancing a crate of luminous sea urchins in both arms. The spiny creatures glowed softly, casting pale light across his scaled face. "Can't you see all those before you? You'll make me drop these, and I'll be the laughingstock of the whole Coral District!"
He grunted, straightening himself and turning to deliver a lecture to whoever had nearly pushed him over. But the words froze on his tongue.
Behind him stood a bullhead shark fishman—tall, broad-shouldered, his skin the color of storm clouds. His lips were twisted into a smile that didn't quite reach his eyes, a smile too still, too deliberate, like the curve of a blade.
The horsehead fishman blinked, uneasy. That smile was wrong. It carried no joy, no reverence—only something dark, expectant. He opened his mouth, thought better of it, and turned back toward the palace gates with a nervous grunt. The line moved slowly forward.
The bullhead shark—Vander Decken IX—barely noticed the chatter and laughter around him. He stood in silence, one gloved hand resting lightly on the hilt of a coral dagger at his waist. His other hand, the right one, was bare. And it glowed faintly beneath the light of the sea lanterns.
Not a reflection—no. The light came from within. A spectral shimmer that pulsed in rhythm with his heartbeat. He flexed his fingers slowly, watching the faint marks that coiled around his palm, like ancient symbols branded into his flesh. The legacy of his bloodline. The final gift of his grandfather—the former captain of the Flying Dutchman.
That hand, he thought, had power enough to claim even a god. Vander Decken's lips curved into a grim smile as he remembered the old man's final words.
"Our family's curse, boy… it binds us to the Sea God. Someday, one will be born again—and she will call to us. To claim her is to rule the ocean itself."
Those words had haunted him. Consumed him. Defined him. While other fishmen dreamed of sunlight or freedom, Vander Decken dreamed of destiny. The Flying Dutchman had passed to him upon his grandfather's death, its deck scarred with generations of obsession. Ever since he inherited the cursed ship, he had trained, searched, and waited as per his grandfather's dying words—for the sign that Poseidon had returned to this world.
And now, at long last, the sign had come. A mermaid princess, born of royal blood. The whispers had reached even the darkest depths of the sea before the palace gates had opened. He could feel it in his veins. She wasn't just any princess. She was her—the Sea Goddess reborn.
Poseidon.