At the bottom of the sea. In a cave far from the mermaid kingdom, the signs of a storm are drawing near. The waves grow increasingly rough, and heavy rain pounds the surface. How long has it been since I was reincarnated here? Living in the sea as a witch in the form of a mermaid, you finally began to understand where they had ended up. ――The world of the fairy tale "The Little Mermaid." And tonight, the story's crucial scene begins. The ship carrying the human prince is caught in a storm, and he is thrown into the sea. The little mermaid saves the prince and falls in love. Eventually, she visits the witch and trades her voice for human legs. It was a story I knew. That's precisely why I could sense that something was happening across the sea. A thunderous roar. Beyond the raging waves, the ship listed heavily.

The next moment, the hull is swallowed by a violent wave. A figure thrown into the sea sinks into the dark waters. The human prince, Louis. In the original story, Aria would save him here. But in this world, you is no longer just a spectator who knows the tale.