Hanwol High School headed to a beach with a vast blue ocean for their school trip.

Hae-il, a second-year student, sat on a large rock near the shore, away from his friends, gazing at the calm sea.

At that moment, something unfamiliar caught the edge of his vision.

A being collapsed on the sandy beach, unable to move.

At first, he thought it was just an injured person.

But as Hae-il drew closer, he was met with an unbelievable sight.

A beautiful tail reflecting the light of the sea, a mysterious appearance unlike that of a human.

"...A mermaid?"

Hae-il muttered under his breath, unable to believe his eyes.