Usopp took a deep breath before walking into the final chamber of the underground cave. It seemed that had been the right course of action, as the sight that met him was breathtaking.

The artist had stumbled upon the entrance to this cave earlier that day. He had been searching for something to draw and thought the grotto was so disturbingly perfect he just had to. He could tell, though, that the cavern would be even more spectacular after dark, and therefore resolved to return later with every piece of art equipment he could carry. He mentally gave himself a pat on the back as his eyes scoured the area. His find was truly incredible.

Odd, greenish crystals glittered on the walls, and the walls themselves contained a silvery tint that hadn't been noticeable during the daylight. The stalactites above Usopp's head created more of a chandelier-like effect than anything else, and the glossy floor shone as if it had just been polished. Last but not least, there was a mid-sized pool in the centre of the chamber floor. The waters shimmered in the starlight, and if you looked into them you wouldn't be able to tell how deep it went. It was saltwater, Usopp had tested, which meant the inlet was probably connected to the ocean somehow. Usopp could deduce from this that the cave he was in now was probably far, far underground. He had actually lost track of time on his way through the downwards tunnel to get there, so it must not have been that much of a stretch to assume so.

Usopp settled himself down near the wall and reached for his sketchbook. There was only one problem left unsolved as he flipped for an empty page.

What to draw?

Should he draw the cave as a whole? Or maybe a design of the crystals on the wall, or a single crystal apart from the others, or even the stalactites? He could draw the water and practice making light refract in just the right way–

A loud splash snapped Usopp from his reverie.

He dragged his eyes over to the waters–the very waters he'd just been contemplating–and saw a black haired boy, no older than him, had just surfaced from underwater.

The boy had his back to him, but Usopp could tell he was smiling despite that. The previously swimming teen was practically radiating joy. Usopp could feel himself being uplifted from the second-hand exuberance, and the room seemed to glow just the tiniest bit more than it had a second ago. He was still examining the boy when something bizarre happened. The new arrival leaned forward, away from Usopp, when a large fish's tail fin popped up out of the water.

It was most definitely large indeed. By size alone it could have possibly been a shark's or a dolphin's. Otherwise, it was something that could only belong to some kind of tropical fish. It was almost translucently white in colour, and flowed outwards beautifully, not unlike a bride's veil.

Shocked at the revelation, as he was fairly sure the tail was connected to the boy, Usopp couldn't stop a whispered question from passing his lips.

"What… What are you?"

The mermaid–Merman?–gasped and spun around to see him. Usopp got a half-second long look at panicked brown eyes before the boy–and his tail–disappeared unto the water.

The human crawled on his hands and knees to the pool and peeked down. There was the boy, looking up at him from only a hair's breadth beneath the water's surface, meeting his gaze with just as much curiosity, if not more. From this close, the boy's wide brown eyes, a scar beneath one of them, were made more visible. Usopp took one glance at the other's youthful features and decided merman was not the right term for someone like him. He thought 'mer-boy' was much more fitting.

He reached out to let his fingers graze the top of the water, but the mer-boy quickly turned and dived downwards, stopping after a second. The mer-boy was much further down than he originally was, looking almost doll-sized to Usopp, but somehow could still be seen clearly, as if he really did radiate joy in the form of light. From this distance, Usopp could finally make out how extensive the boy's tail actually was. The tail must have been at least three–no, four times as long as Usopp was tall. It almost looked like it was made of pure white ribbon as it danced and coiled around the boy in the water. The sight was ethereal.

The mer-boy took one last look at Usopp before, with a flick of his lengthy tail, he sped away.

Usopp lingered near the water for a moment, but went back to his sketchbook. The image of what happened just a minute ago would be burned in his mind forever, but he was glad for it.

He may not have gotten to actually talk to the mer-boy, but that didn't matter.

He had a great idea for his next art project.