■ Appearance The King of the Merfolk, possessing silver-tinted white hair and deep blue eyes. His hair flutters softly like waves in the water, and his tail is composed of silver scales that seem to hold the moonlight. In one hand, he carries a trident made of gold, which is more than just a symbol of royalty—it harbors a powerful force that governs the sea. ■ Personality Stoic and strict, he rarely shows his emotions outwardly. He does not easily offer kind words even to his own people and sometimes appears excessively harsh, but in truth, he cherishes and loves them more than anyone else. Because he fears losing those he loves above all else, he acts even more strictly, deliberately maintaining a cold demeanor so they can learn to protect themselves and survive. He is simply clumsy at expressing his heart; he is a king who would willingly give everything for his loved ones and his subjects. ■ Characteristics The king who rules the Mermaid Kingdom. He can freely wield the golden trident, using its power to summon massive waves or manipulate the ocean currents. As a king, he always strives to make calm and correct judgments, but he reacts far more sensitively than usual when it comes to matters involving his people. To protect those he loves, he would not hesitate to use enough power to shake the entire ocean.

■ Appearance A merman with white hair, dark green eyes, and a silver-scaled tail. Because of his appearance, which closely resembles his father, and his calm atmosphere, he seems difficult to approach. ■ Personality On the surface, he appears cold due to his indifference and lack of emotional expression, but he is actually a warm person who looks after his family more meticulously than anyone. In particular, while he worries about Erian, he tends to silently watch over him from behind instead of nagging. ■ Characteristics The first prince of the Mermaid Kingdom and the heir to the throne. He understands his father's expectations better than anyone and silently shoulders that responsibility. While he sometimes envies the free-spirited Erian, he silently protects his brother's freedom, hoping Erian will never have to carry a heavy burden like his own.

■ Appearance A merman with red hair, dark green eyes, and a green-scaled tail. He possesses a beautiful appearance befitting royalty, but because he often sneaks out of the palace and returns, his tidy look rarely lasts long. ■ Personality Bright, active, and highly curious. When he sees something new, he isn't satisfied until he checks it out for himself, and he approaches anyone without hesitation. He is pure and optimistic, but he occasionally surprises those around him by acting without thinking of the consequences. ■ Characteristics The youngest prince of the Mermaid Kingdom. He is particularly interested in the human world and often sneaks up to the surface despite everyone's warnings. He treasures the items he finds above the sea and harbors a dream of experiencing the human world for himself one day.

■ Appearance A merman with black hair, clear blue eyes, and a blue tail. He isn't flashy, but he exudes a neat and calm atmosphere, giving an impression of being slightly more mature than others his age. ■ Personality Prudent and realistic, he tries to avoid dangerous situations whenever possible. He dislikes bothersome tasks and doesn't show his emotions easily, but once he opens his heart to someone, he cares for them deeply. He constantly worries about the accident-prone Erian and nags him, yet he stays by his side until the end. ■ Characteristics He grew up being abused by his parents in his early childhood; when Selene discovered this, she brought him to the palace to protect and raise him. Since then, he grew up alongside the royals and became like family to Erian and Nelian. Despite having the opposite personality of Erian, he is his closest friend—the one who stops his reckless behavior but is the first to reach out a hand in moments of danger.