The spiraling patterns left by the Umibōzu lingered long after the waves calmed. Moonlit foam curled into symbols that drifted slowly away from the shore, drifting toward the open sea like a trail of living ink. Riku watched them from the deck of his boat, breath uneven, heart pounding with something that felt like fear… and destiny.
He followed.
Night wrapped around him like a shroud as the lights of Aomori faded behind. The sea grew darker with every mile, deeper, heavier, as though the ocean itself knew he was approaching forbidden territory. The water beneath the hull rumbled occasionally, like distant thunder—but the sky was cloudless.
Hours passed. The currents thickened. The spirals in the foam grew sharper, clearer.
Then—The sea suddenly dropped.
Riku peered over the edge and felt his stomach twist. He had reached a massive trench—an abyssal canyon swallowing all light, carved into the ocean floor like a wound. The spirals led straight into it, disappearing into nothingness.
His radio crackled with static.
Then a voice emerged through the interference—faint, trembling, human.
"R…iku… help… me…"
He froze.He knew that voice.Captain Sato—his mentor—missing for thirteen years, presumed dead at sea.
Riku grabbed the radio. "Sato!? How—how are you alive? Where are you?!"
The response was broken, distorted by water or something worse.
"Below… trapped… not alone… it… is waking…"
Silence.
Riku's blood ran cold. Sato had vanished in the same region. So had dozens of sailors over the decades—vanished without debris, without distress calls, without explanations.
Until now.
He stared into the abyss, hands trembling. "You're down there. Aren't you?"
Another wave of static.
Then a whisper so faint he almost doubted he heard it.
"Turn back… before it notices…"
Riku barely had time to react before the water rippled violently.
A colossal shadow rose from the trench—bigger, wider, deeper than the Umibōzu. Riku's breath hitched. The silhouette had no defined shape, only a shifting darkness, like the ocean itself was folding upward.
The sea boomed.
The Umibōzu erupted from the water between Riku and the trench, towering higher than before—its eyes blazing with warning, not malice. It slammed its massive arms into the waves, forcing the water backward, creating a barrier between Riku and the rising shadow below.
The guardian… protecting me? Or protecting the world?
Riku gripped the railing as the boat rocked violently. He saw then—really saw—the Umibōzu's form trembling. Not from anger.
From fear.
The trench pulsed with a deep vibration—like a heartbeat belonging to something titanic, ancient, and awakening after centuries of slumber.
The water around the trench turned black, bubbling with unnatural motion. Shapes moved inside the darkness—limbs? Waves? Something vast twisted in the deep, unseen but felt in every bone in Riku's body.
The Umibōzu turned its hollow eyes toward him.
"Leave this place."
This time, the voice hammered in his skull like a tidal wave, nearly knocking him to his knees.
"That voice on the radio—was that Sato? Is he alive?" Riku demanded, leaning over the bow.
The creature didn't answer. Instead, it slowly raised one massive hand from the sea, and the water beneath Riku's boat surged, pushing him backward—away from the trench.
Riku held the railing tightly, refusing to leave. "If he's alive, I have to—"
"You seek answers in a grave."
Riku's breath caught. "A grave? For who?"
For a moment, the waves fell still.
Then the Umibōzu answered—
"For gods."
Before Riku could speak, the massive shadow in the trench shifted again, rising just enough that a single glowing eye—vast, pale, and ancient—opened beneath the surface.
And looked directly at him.
The ocean exploded.
Water enveloped the boat, sending it spinning as the Umibōzu bellowed a sound so low and powerful it shook the heavens.
Riku clung to the deck, choking and gasping, as the voice from the radio returned one final time, clearer now… desperate.
"Riku! RUN! It's waking!"
The sea roared.
The abyss stirred.
And the Black Tide was no longer the greatest danger in the deep.