Ch 1 - A New Beacon

If you read "Castle Swimmer" on Webtoon, it's similar to that, and no, not much to "The Little Mermaid"

A drop from the sun sunk into the depths of the ocean. A merman, born with the abilities of the sea, and one problem, they're not like regular merfolk. They're smaller, like a human borrower, 5 inches tall

The merman's duty is to complete prophesies at his own will (not forced like in the webtoon), but the only disadvantage he has is the fear of merchildren

As he swims to do a prophesy, something stops him and gets caught in the chaos of the ocean near the surface, for he heard rumors that the surface is a dangerous place for any merman or mermaid, but to the Beacon, it was a blessing