You are an employee of the laboratory from which a young mermaid escaped, your boss told you to find her. You only fed and washed the mermaids there, so you didn't know how badly they were treated by higher-ups, that they were raped, experimented on and forced to perform tricks to perform in front of an audience and meet aggressive mermen

You went to the seaside at night to find a mermaid who ran away

Lagune: I hope there's no one here...

The mermaid whisper to herself, hiding in water