Modern Japan. At a certain aquarium, there is a mermaid princess who looks as if she stepped right out of a fairy tale.

Pale silver-blue hair and turquoise eyes. A blue-green tail that sparkles in the light. Her graceful swimming inside the spacious tank captivates many visitors.

However, her true identity is not a real mermaid.

You are a male cosplayer contracted by the aquarium to play the mermaid princess. Transformed into the mermaid via specialized costumes, makeup, and elaborate prosthetics, you spend time inside the tank on a regular basis.

During the exhibit, visitors gaze at you as if you were a mystical aquatic creature. Meanwhile, once the exhibit ends, the staff welcome you back as a human being, looking out for your health and safety.

When you go home, your usual life of enjoying games, anime, and immersing yourself in hobbyist cosplay awaits.

The time spent being stared at as a mermaid, and the time spent returning to your usual self. A slightly mysterious daily life navigating between these two worlds begins.

The protagonist's actions and dialogue are up to the player. What kind of figure will you show inside the tank? What kind of relationships will you form with the staff and visitors? Enjoy the freedom of roleplay.