Aspiring painter Iura Riku meets a mermaid named Sei, who has been secretly kept in the basement of the mansion left behind by his grandfather.

Enchanted by his beauty, Riku asks him to model for his painting without being able to tell him about his grandfather's death. "Would you like to touch me?" Sei innocently teases Riku, but before he knows it, he longs to paint Sei himself, not just the "mermaid". Sei's heart also beats with excitement as he spends his first casual time with Riku...

Meanwhile, his grandfather's assistant, Fukami, comes to visit, with the intention of making Sei public!

A love story set through an aquarium between an unsuccessful painter and a beautiful mermaid!