It starts with a deep blue. Dawn slices across the restless surface of the Umbra Sea. Yuto Ronin, 17, leans over the gunwale of the weathered cutter Selkie, one steady hand gripping paint-chipped wood. He can’t look away from the ocean below. Is the water holding secrets tighter than his city ever could? Kiriko, tomboy crew engineer with her goggles pushed up, shouts up to him: “Done staring? Sun’s up, so let’s not ram an islet for a change!”
For Yuto, it’s his first time leading this small group—it weighs on him. They’ve left their city-port behind in search of vanished science ships, drawn by whispers of a glowing city that sings beneath waves. Ko Sazanami, the skittish scholar, sorts through soaked notes in the low light. Captain Ohga isn’t with them; the elder vanished last week offshore, leaving Yuto no choice but to keep his crew from falling apart. Ever led people through hurt you barely understand yourself?
A storm closes in as the Selkie follows coordinates lifted straight from coded logs. Kiriko curses, fighting cogs to keep their engine from choking on salt. Rain hammers decks. The ship heaves, wild and alive. Ko yells: “We must change course—folk tales warn about the ‘Yurei Shoals’ swallowing ships right where Captain Ohga vanished!” Yuto stands his ground. He’s chasing hope; maybe it’s the only thing keeping his crew together.
The cyclone breaks the ship’s mast. For hours, all is chaos. Then, a sudden calm. They’re adrift over unknown, pale blue water. Dead quiet. No waves.
Kiriko speaks first: “This is wrong. Nothing’s moving under us.” Under the still surface, glowing towers and broken, gilded iron beams shiver with eerie green brilliance. Ancient ruins reveal themselves between swaying fronds, slow and arranged like city alleys winding far below.
Yuto finds strength. “We found it! But, can we get down there?” They peer overboard. Ko’s scanner picks up signals, staticky but honest: the codes match those from missing science ships. Kiriko fixed their submersible pod in secret; her trust and stubborn hands turned drifting junk to something that might save them all. That breaks any tension in the air. Yuto says: “We try together, or we lose even the journey.”
They enter the gloom below, led by Yuto but resting on their bright, tired unity. Kiriko pilots, Ko balances between fear and sharp-focused glee over glimpses of strange tuna and bioluminescent sharks chasing near-lit ruins. Yuto can’t help but smile.
In the city’s maze they spot signs of other unlucky crews—lost markers, fire-lit patterns on slate, empty packs drifting like dark jellyfish. Ko’s recorder flashes red warnings, but this draws them deeper. Have you ever felt that paradox: the closer you are to solving a thing, the stranger it all feels?
From shadows ahead comes a call like a memory half-heard. Kiriko shoves forward; she thinks she sees someone she once lost to these waters. Ghost or rescue beacon? Yuto resolves they must press on, giving his hope and old grief to propulsion. There’s movement ahead: gold eyes deep inside the city. If only Captain Ohga is near—but Yuto can’t shake the sense nothing in this city gives without a cost.
Up above, a signal crackles through their comms. A rescue beacon? The same call that drew in the others now spikes—then shifts pitch, veering wild. Is that just distorted code…or is someone alive down there using their channel? Kiriko pounds the controls, shouting: “No way. This thing…it’s answering us.”
As floodlights sweep across the city heart, what they thought were statues begin to stir. Tower shadows collapse, shaping into figures that don’t match any biology manual. Ko, stunned: “I thought only crabs lasted this long underwater!”
At the very base of the luminous city, an orb pulses—half-machine, half-coral. A broken visor blinks. Captain Ohga? Before Yuto can assess, the entire crew gets caught in the electric net binding city to sea, and the sub loses all power.
Kiriko strains in utter black: “Yuto! Which way is up? I can’t even hear water rush!” Silence or pressure cuts between heartbeats. Ko clings to Yuto, above their heads old Selkie ghosts sing, and a silhouette reaches out from near the pulsing orb.
Last picture: Yuto opening the sub’s side-hatch, light pouring out as voices and memories pile into the tiny space. The pulse shifts blue, and something older than myth answers their crew’s desperate song for home…but is it a rescue or a test?
End of episode. The signal’s full story waits beneath black water.
