Prologue: Fog on the Waterfront
Docks groan as midnight fog rolls with the tide. Masato, a shy apprentice diver, listens to the soft drip from corroded barrels. Have you tasted dread just before something moves in the dark? He’s seen bodies—stripped and marked—as if something hungry drags them from the depths. Police chalk it up to the city’s crime, but even they avoid their own patrols after dusk. Masato, driven by an urge to find his missing brother Jun, hides behind crates and clutches Jun’s red diving mask. He whispers, “I won’t lose you again.” Shadows ripple beneath the oil-black water.
Characters Meet: The Survivors’ Pact
By dawn, news of a fresh corpse sweeps the slums. Daichi, all fists and snark, catches up to Masato. Emi, who speaks softly to stray cats and isn’t afraid of much, watches the water with them. Daichi spits out, “So, still think this is ‘some big fish’?” Emi nudges him, locks gaze with Masato. “You scared?” Masato can’t keep from trembling. He mutters, “I’m still going. You don’t have to come.” There’s green wire in Emi’s satchel. Daichi, secretly worried, shrugs. “I’ll bring a stick. And if you run, I’d better see your back for once.”
The Fisherman’s Tale and First Descent
An old fisherman, six rotten teeth and more stories, finds them with his eyes crossed at the tide. “The eater in the tide—old families fed it, kept it perfect,” he hisses. “One day someone stopped the food, so now it takes!” He draws strange marks in the dirt. Daichi says, “Did he just curse us?” Emi ties twine at her waist. Masato puts on Jun’s mask and replies, quiet but sure, “Maybe. Doesn’t matter now.” Their plan: dive at low tide, follow old rumors, see if ‘the eater’ is real. Everything hinges on Masato’s grit and that red mask everyone wants him to leave behind.
Descent and Discovery
The river’s clotted under the crumbling bridge—a place folk cross fast and never look down. The gang’s feet slap rotten boards. Emi pulls out her tiny camera; Daichi tucks a rusted knife into his belt. Masato’s chest burns; each breath tastes metallic. Water laps cold as he slips over the side and searches below. Through the fog, a shape with glacier-white arms floats by: a corpse stitched all over as if someone or something wanted to keep pieces from running away. 
Poor light, twisted metal, slime smothering the bank—out of nowhere Jun’s red mask pops free from weeds, face up. Did he vanish here? Big floodgates leer above, locked till night. Emi finds a strange coin in the dirt, a serpent wound tighter than spring steel. “This wasn’t here before,” she says. “That’s how it calls,” the old fisherman shouts back from shore.
The Attack: Teeth in the Water
Nothing stirs. Then, rippling sound—a scraping, loud then hollow. Daichi starts to curse, but something strong as a bull yanks him down. Only his muffled cry and a splatter of reeds break the calm. Water boils. Masato lunges, wild panic—he grabs Daichi’s collar, Emi tosses a line, the old man’s sobbing a prayer. They yank and lose grip—the thing surfaces—huge maw full of split bone, eyes cloudy as old jellyfish. It’s part snake, part centipede, mouth tucked with human teeth, russet hair caught in the weed-braids along its back. You ever think something would rather you screamed?
Escape and Haunting
They scramble to safety. Whole blocks away, soaking, the trio shoves through locked doors into Emi’s half-lit flat. Bones ache. No comfort in their white faces. Daichi grumbles he never wants to, “see a worm in my fruit again.” Masato shields his eyes with the mask. Still, something calls. He dreams his brother, voice thick—“Little fish, hide in me, not from me.” Jun in chains below black water. Masato wakes clawing at Emi’s arm. 
Hunt for the Ritual
Everywhere, fresh symbols. On the pier carved in blood. Kids talk about a traveling priest who’s paid to keep monsters happy. Emi presses, “Does a city buy its peace with death?” Daichi says, “Why not kill it instead?” Not so easy. Legend says anyone who tries goes mad. They gather incense, borrowed relics, the mask as bait. Night comes thick again. Who’s going to face a god that feeds and hates both?
The Deep Core: Showdown Below
Inside the oldest drain under the wharf, torch beams bounce on weird carvings. Wax puddles in rat-smart lines. Something moans below—a hundred voices, too many. Masato slips, plunges knee-deep into black. Daichi hauls him by the jacket. “Don’t scream. Don’t answer it,” Emi hisses. The snake-centipede, twice the size as before, watches from a well below, pink tongue split and flicking. 
A Price for Passage
They chant, break the serpent coin, and pray. Water whirls. The beast looms up, mouth unhinging, eyes set on fire. Masato sees part of Jun’s diving suit tangled in its spine. Blood froze? Maybe yours too. You ever see a thing holding itself together with someone’s hope?
Cliffhanger: A Pact or a Sacrifice
Pain—white, sharp, steals Masato’s breath—the beast swings close and actually speaks: “You will feed me, or vanish with the old ones.” Spotlights flash; incantation explodes in heat; Emi screams for Masato to run as the monster pulls him half-under the raging water and Daichi wades after, swinging the knife.
In the last shot, Masato and Jun are face-to-face under water, eyes wide, link unbroken. Everything fades. Do you dare descend next week? 
