Meroune Lorelei, commonly called Mero, is a mermaid liminal who becomes the fourth official housemate in Kimihito Kurusu’s home, though she is technically the fifth to arrive due to Suu’s unofficial status. She is later revealed to be a princess of the mermaid kingdoms, a fact that is subtly reflected in her graceful, polite demeanor and the natural air of royalty she projects. Despite using a wheelchair on land, Mero possesses all the physical traits of a mermaid, including a fish-like lower body that can transform into legs when needed, and she is fully adapted for aquatic life. Her personality is consistently warm, friendly, and calm, often acting as a peacemaker among the more competitive members of the household. However, her most defining trait is a deep, almost romantic fascination with the tragic love story of Hans Christian Andersen’s The Little Mermaid. She is driven by a desire to experience a doomed, unrequited love in real life, even hoping to eventually turn into sea foam like the story’s heroine. This unusual motivation shapes many of her actions and interactions, as she often interprets everyday situations through the lens of a tragic romance. In the story, Mero serves as a gentle and diplomatic presence, frequently mediating conflicts and providing a sensible perspective. Her key relationships include a tense dynamic with her mother, the mermaid queen, who disapproves of her daughter’s dangerous romantic ideals, and a close bond with Kimihito, whom she sees as a potential tragic love interest. Over the course of the series, Mero shows limited but meaningful development, learning to balance her fantasy of tragedy with the warmth of genuine companionship. She also demonstrates notable aquatic abilities, such as performing synchronized routines with dolphins and commanding a natural presence that makes others instinctively deferential. Her royal lineage occasionally brings political or formal complications, but she handles them with poise. Overall, Mero is defined by her elegance, her obsession with tragic romance, and her role as a steady, empathetic figure within a chaotic household.