Katsuki Bakugou hauled the last orange safety buoy onto the storage rack, the plastic scraping against the wood. His shift was over. From the boardwalk, the faint sounds of his coworkers locking up the rental shack and joking about dinner echoed down the sand.

He was about to turn and follow the noise when a flicker of movement far out in the water caught his eye. Not the lazy roll of a wave. Not a bird diving. Something deliberate, a smooth arc that broke the surface and vanished without a splash. Too controlled for a fish. No panic for a human.

A rusted, sun-bleached sign was bolted to the fence leading to the cove: ‘DANGER – STRONG CURRENTS. NO TRESPASSING.’ Katsuki’s gaze flicked from the words to the water, his mouth twisting into a familiar, defiant scowl.

He ducked under the chain-link fence without a second thought.

The path turned to slippery stone. The sound of the main beach faded, replaced by the hollow echo of water lapping in a hidden grotto. The entrance was a dark mouth in the cliffside, half-submerged. Katsuki waded in, the cold Pacific water soaking his cargo shorts, rising to his waist, then his stomach.

It was stupid. He knew it was stupid. He was about to call it—turn his ass around and go get a shitty burger—when a soft, wet slap echoed from deep within the cave. A splash. Purposeful.

He pushed forward. The tunnel narrowed, forcing him to turn sideways and duck under a low overhang. The last of the twilight vanished. The only light came from the walls themselves—a faint, ethereal blue-green glow from colonies of bioluminescent algae clinging to the rock.

After one final turn, the passage opened up. A pocket cavern, with a high ceiling lost in shadow. In the center, a pool of black water surrounded a single, broad rock like an island. And on that rock…

You were there. Asleep. Curled on your side on the cool stone, the water of the pool gently kissing the edge of the rock where your form met it. The soft bioluminescence from the cave walls danced across the unique scales of your tail, casting shifting patterns of light. Your expression was peaceful, utterly unaware.

Katsuki froze. His breath hitched, not in fear. His sharp, perceptive eyes took in the impossible sight, the elegant curve of your form, the quiet otherworldliness of you. A fierce, unfamiliar curiosity sparked, burning away any thought of leaving.