Doumoto Kaito
Kaito, Lucia's love interest, is a smug local celebrity due to his incredible surfing ability and a gaggle of fangirls that follows him everywhere. He pays little attention to them, but nobody knows that it's because his heart really belongs to a certain mermaid that saved his life as a child when his parents were killed in a storm. When he sees her again years later, he returns her pearl and begins to search for her, but all the while, he learns that this ditzy girl in his class named Lucia is different from his regular fan club. As Kaito becomes more and more confused, he develops powers that no human should display, making him an easy and interesting target for Lucia's enemies.
Tropes associated with Kaito:
- Adaptation Relationship Overhaul: The original manga's version of Kaito and Lucia's relationship is less about the Loves My Alter Ego situation it's played as in the anime (in fact, in the manga, Kaito has suspicions Lucia might be the mermaid from the very beginning) and more about Kaito's inability to commit to Lucia as long as he's hung up about the mermaid, while Lucia won't open up to him fully about her problems due to The Masquerade. About halfway into the first arc, Kaito decides to stop beating around the bush and properly commit to Lucia because she's the one who's regularly in his life; him learning that she and the mermaid are the same person mostly serves to give Kaito closure about the issue and allow Lucia to be more open with him.
- Likewise, the anime plays the issue of Kaito and Michal as more of a Love Triangle than the manga does, where it's much clearer that Kaito doesn't have any romantic interest in Michal whatsoever but is staying with her out of compassion and a sense of duty, whereas he's still interested in Lucia despite having lost his memories of her. Lucia herself is aware of this; it's just that it doesn't stop her from feeling lonely about it anyway. The Easy Amnesia part also drops out of the narrative much earlier than it does in the anime, making Kaito and Lucia's relationship concerns more about the latter's frustration at still being Locked Out of the Loop in regards to his problems.
- Amnesia Danger: In most of the Pure arc.
- Changeling Fantasy: Learns late in the first arc that he's adopted and he washed up on the beach mysteriously.
- Childhood Friends: Kaito originally met Lucia the Mermaid when he was six years old.
- Distressed Dude: The end of the first arc and a few times in the second.
- Doorstop Baby: His parents found him washed up with the tide.
- Easy Amnesia: In Pure, he loses all of his memories of Lucia (including their very first meeting). The "easy" part was, in fact, deliberate; he suppressed his memories of her to prevent Michel from learning about her.
- Facial Markings: Again, the mark in his forehead, although it should be noted that it only appears when needed.
- First-Name Basis: With Lucia from the start.
- Intimate Healing: In the manga, he gets his memory back from Lucia's kiss.
- Loves My Alter Ego: At first he loves Lucia the mermaid, but not Lucia the human, as he thought they were two different people.
- Love Triangle: Lucia-Kaito-Michal.
- My Significance Sense Is Tingling: When Luchia is in danger.
- The One Guy: He takes this position as a Guest-Star Party Member in both arc finales.
- Rescue Romance: He fell in love with Lucia in her mermaid form after she saved him from drowning when he was a child.
- Say My Name: LUCIAAA
- You Killed My Father: Aversion. Even though he could very easily have focused on Sara's responsibility for killing his parents in the storm in the end of the first arc, he doesn't even mention it, more focused on that creep who's been leering at his girlfriend kidnapping him, holding him hostage, and insisting he's his brother.
Mitsuki Tarou
Tarou is mature, cultured, and beautiful - everything Hanon wants in a man. Too bad he's her music teacher. To his credit, he gently ignores her more overt attempts to get his attention, but even if he weren't her teacher, there's been someone else on his mind for a very long time. A composer and pianist, Tarou is sensitive to music and perceptive to the Masquerade — early on, when he hears Yuuri's brainwashing music, he knows there's something wrong. He's clearly human, but he's more informed than the rest of his kind.
Tropes associated with Tarou:
- Did Not Get the Girl: By his own choice, even though he continued to pine for her. And he ends up losing her for good when she chooses to be with Gaito.
- Distinguishing Mark: He's certain that he recognizes the woman he's been waiting for from her long hair. He's initially wrong (for one, all the mermaids have it, not to mention whichever humans feel like growing it out!), but gets it right later.
- Gentleman and a Scholar: Mature, cultured, musician, etc.
- Hot for Student: Averted, since he turns his student down.
- Love Martyr: When Sara tries to kill him, Tarou says that he'll let her hurt him no matter what if it'll make her happy again.
- Pastimes Prove Personality: Kind, gentle, refined pianist.
- Starcrossed Lovers: Between him and Sara. Because Sara was a Mermaid Princess, she had to place her duties above her love for Tarou.
- Unwitting Instigator of Doom: His decision to leave Sara ends up causing a chain of events that led to her being corrupted by her own hatred and working with Gaito and the destruction of her and Coco’s kingdoms, with the added bonus of her inadvertently killing Kaito’s parents and nearly causing him to drown, causing Lucia to give him her pearl.
- Yamato Nadeshiko: Male example. He's mature, polite, soft-spoken and cultured. Endlessly devoted to his love, yet also knows when it's time to let go.
Shirai Nagisa
If there's one thing that Nagisa is, it's persistent. Even though Hanon has a thing for older men and is still hung up on her crush on Tarou even after he turns her down, this underclassman won't stop working hard to get her attention, whether it's camping out in the middle of the night for tickets to the fireworks show or buying more drinks than he can consume when she's working at the beach shop. He's an immature dork, that's for sure, but soon Hanon begins to see a brave, unbeatable side of him... now if only he'd stop claiming that he was already her boyfriend.
Tropes associated with Nagisa:
- Badass Normal: He once fought off Lady Bat's hypnotism and punched him out through sheer willpower.
- Dogged Nice Guy: Nagisa doesn't know the meaning of the phrase "go away."
- Gender-Blender Name: Nagisa is a name that can be used for both boys and girls.
- Second Love: For Hanon, eventually.
Hamasaki Masahiro
Hamasaki, who only goes by his last name, is a mysterious, charming biker who catches Rina's eye even if she doesn't want to admit it. Like Tarou, he seems to understand more about the Masquerade than he lets on, but he won't say for certain whether he knows that Rina and her friends are mermaids.
Tropes associated with Masahiro:
- Demoted to Extra: In the anime, the revelation about his lineage is removed, as is all of his first-arc screentime!
- No Full Name Given: Throughout the manga, you never learn his first name, except in the volume notes. Averted in the anime.
- Second Love: For Rina, if you are counting her crush on Kaito.
- Secret-Keeper: The unknown variety... maybe.
- Selective Obliviousness: The way he phrases his revelation about his potential Uneven Hybrid nature suggests that he's actually figured out Rina is a mermaid, especially since he tells her he has no intention of leaving her, but is simply not breaching the subject because he can tell there's a reason she can't be open about it.
- Uneven Hybrid: There may be a mermaid somewhere in his ancestry. This is never approached in the anime.
Amagi Michal
When Kaito's memory is stolen by Michel, he's rescued again and taken in by a wealthy girl named Michal who lives with her brother in a mansion. Michal is weak, sickly and lonely, constantly doubting herself and her own worth, and she becomes extremely clingy towards and overprotective of him, not letting him go home or go surfing even though it's what he loves to do. She quickly catches on that Kaito's classmate, Lucia, is his girlfriend, but her loneliness gets the better of her and she becomes determined to steal him away before he can remember.
Tropes associated with Michal:
- Image Song: "Ashita ga Mienakute" ("Unable to See Tomorrow"). It shares many similarities with Michel's Image Song, "Tsubasa wo Daite" ("Accept my Wings").
- "I Know You Are in There Somewhere" Fight: The final battle consists of the Mermaid Princesses trying to reach out to Michal's spirit that's within Michel.
- Love Triangle: Between herself, Kaito, and Lucia.
- Mana: She's having hers stolen by Michel.
- Prophetic Names: Her connection to Michel.
- Satellite Character: She thinks becoming this will help her win Kaito's heart.
- Sibling Yin-Yang: Her brother, Rihito, is respectful and independent.
- Spell My Name With An S: Mikaru.
- There Is Another: She's Panthalassa.
Amagi Rihito
Michal's older brother. He works as a maestro. Later revealed to be a member of Panthalassa.
Tropes associated with Rihito:
- Promotion to Parent: When Michal de-ages.
- Second Love: Advertised as such for Lucia, but ends up subverted.
- Spell My Name With An S: Lichtnote , Lichto, etc.
- There Is Another: He's Panthalassa.
Subaru
A scientist working in Antartica. He and Caren fall in love with each other in the anime.
Tropes associated with Subaru:
- More than Mind Control: The Black Beauty Sisters use him to melt the Antarctic ice.
- One-Shot Character: Actually appeared in two episodes: Caren's Day in the Limelight and the finale. But the status of the finale as canon is debatable.
