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Characters / My Bride is a Mermaid
aka: Seto No Hanayome

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These are some of the characters from My Bride is a Mermaid and tropes that are associated with them.

This page is currently under construction. Any contributions are appreciated.

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"What is wrong with the adults in my life? I might as well go steal a motorcycle."
Nagasumi Michishio
  • Art Shift: Whether it's to Super-Deformed or to Fist of the North Star it's always for comedy.
  • Battle Aura: When someone generates one of these, it's usually played for laughs.
  • Bizarre Alien Biology: When exposed to water a merfolk's legs will turn into fins.
  • Curtains Match the Window: Sun has light brown hair and eyes, Lunar has pink hair and eyes... the list goes on.
  • Cute Monster Girl: Female mermaids in mermaid form are entirely human above the waist.
  • Involuntary Shapeshifting: Young mermaids cannot maintain their legs if they get wet.
  • Love Dodecahedron: Most of the female characters with the exception of Saturn and Jupiter, both of whom are gay, fall for Nagasumi.
  • Make Me Wanna Shout: Female mermaids can use their voice as a weapon.
  • Mermaid Problem: Downplayed. Adult mermaids can transform their tails into legs at will and younger ones can still maintain human legs until their legs get wet.
  • New Transfer Student: Starting with Sun because her husband goes to that school.
  • Our Mermaids Are Different: Teenagers can pass for human most of the time and adults can pass for human all the time.
  • Theme Naming: A lot of mermaids have the name of an important body of water in their family name and a celestial object as their given one.
  • Threesome Subtext: Nagasumi, Sun and Lunar, who all live together. Especially so in the manga, where Lunar outright says she wants to stay with both of them forever.
  • Voice of the Legion: Whenever a female mermaid uses her voice to attack, they can speak as if many voices are heard at once.
  • Why Did It Have to Be Snakes?: Most mermaids (since they are technically fish) are afraid of cats. Most of them get over this fear as they grow up.


     Nagasumi & Sun 

  • Battle Couple: At the end of the series for the Final Battle when they confront the final villain together.
  • Chastity Couple: They're engaged by the end of the first episode but for the bulk of the series they're no more intimate than Holding Hands.
  • Innocent Cohabitation: Sun moves into Nagasumi's home. They're in different rooms.
  • Interspecies Romance: Nagasumi's a human, Sun's a mermaid.
  • Official Couple: The fulcrum of the plot is their engagement.
  • Rescue Romance: Played with; they first meet when Sun saves Nagasumi from drowning, but they don't genuinely fall in love until later.
  • Shotgun Wedding: It was either get married or one of them would have to die.
  • Sleep Cute: In episode 13 The mafia war turned singing festival wore them out.

Nagasumi Michishio
Voiced by: Takahiro Mizushima (Japanese), Todd Haberkorn (English)

A high school student from Saitama who nearly drowned during his holiday at Setouchi. He was rescued by Sun and subsequently had to marry her so neither would be executed for breaking the Masquerade.

Sun Seto
Voiced by: Halko Momoi (Japanese), Alexis Tipton (English)

The daughter of Gozaburo & Ren Seto, the leaders of the Seto Clan. She saved Nagasumi's life, but in doing so broke the mermaid's code of secrecy. Rather than having one of them die, Sun went with a third option in marrying him.

  • Action Girl: In the words of her fiancé: "Once she gets a sword in her hands she's like a completely different person".
  • All Girls Want Bad Boys: One episode has Nagasumi imbibe a love potion that makes him look like he's every girl's type. When Sun looks at him in that state, she sees a Jotaro Kujo Expy.
  • Alliterative Name: Sun Seto.
  • Always Someone Better: Was this to Lunar growing up, as Sun always beat her in singing contests. To this day, Lunar still holds a grudge.
  • Badass Adorable: She's sweet and clumsy and cute but also the daughter of the mafia.
  • Betty and Veronica: She is the Veronica (mermaid yakuza) to Mawari (human childhood friend) and the Betty to Lunar (glamorous pop star).
  • Beware the Nice Ones: Sun may be a Yamato Nadeshiko, but she is also a Mafia Princess and master swordswoman more-than willing to fight in the defense of her loved ones. In another example, Maki, her tiny bodyguard, usually doesn't seem to respect anyone but Sun and Gozaburo. After she went a little too far in trying to reveal Akeno as a mermaid, Sun scolded her about it and Maki seems genuinely terrified during that lecture.
  • Boobs of Steel: Her swordsmanship and ample bust make it perfectly plain.
  • Breast Expansion: Ironically, her breasts actually look larger than normal when she's in "Sunpachi Setojima" mode.
  • But for Me, It Was Tuesday: When Lunar reminds her of the singing contest she lost against her as a child, Sun sheepishly admits that, with everything that happened to her since then, she forgot about Lunar.
  • Buxom Is Better: Saru lists her bust size as one of the reasons she's so popular.
  • Calling the Old Man Out: A minor example; when Shark Fujishiro attacks Nagasumi at the Obon festival under her father's orders, Sun demands that Gozaburo apologize to Nagasumi, telling him that she "can't respect a father who won't even act like a man."
  • Catchphrase: The alternate way of reading 'Ninkyo'(Chivalry) 'Ningyo' (Mermaid)!
    • In the English dub it becomes "Because honor among thieves is honor under the sea!"
  • Cherry Blossom Girl: She is associated with cherry blossoms, is the main love interest, and is a Yamato Nadeshiko.
  • Cherry Blossoms: She gets it from her mom, and busts them out whenever she's feeling dramatic.
  • Cute Clumsy Girl: When she's nervous she gets klutzy, which is quite a problem when she's around water, as it turns her back into a mermaid.
  • Damsel in Distress: In the climax of the anime she is kidnapped and drugged by Yoshiuo.
  • Face Death with Dignity: She is fully prepared to accept death as a result of saving Nagasumi and breaking The Masquerade. Thankfully, Ren decides to Take a Third Option.
  • First Girl Wins: First girl introduced and the one Nagasumi stays devoted to.
  • Gainaxing: During Sun's contest against Lunar in the anime, she jiggles quite a bit. In the manga's pool chapter this is the reason all the boys are staring at her and Akeno.
  • Hair Intakes: Her hairstyle has a pair of what kinda look like cat ears.
  • Hidden Depths: Sun is very knowledgeable about the Yakuza world and the different criminal activities they operate, which makes sense considering she'll be the next head of the Seto clan.
  • High-Pressure Emotion: After trying different poses in front of a mirror with a pair of cat ears, her face heats up like a steam boiler due to embarrassment.
  • Innocent Fanservice Girl: She has no clue as to just how attractive she is to so many people.
  • Instant Fan Club: Latent until Lunar showed up. Then suddenly she had her own militant faction that was willing to kill her fiancé for more of her attention.
  • Japanese Delinquent: Her Sunpachi Setojima persona involves her invoking as many of the tropes associated with this as possible from clothing to speech patterns.
  • Ludicrous Melee Accuracy: Sun is so skilled a swordswoman that she can cut through clothes and leave the person wearing them unscathed.
  • Madness Mantra: When every other mermaid character (except Jupiter) and Saru's little sister announce they are in love with Nagasumi, Sun begins chanting "I have faith in Nagasumi..." in a Creepy Monotone until she collapses from stress.
  • Magical Girlfriend: Sun is a sweet and beautiful mermaid who saves the life of the normal human Nagasumi and by the rules of her clan, she becomes his devoted fiancée so neither of them have to die. This results in a sheer amount of craziness for Nagasumi.
  • Magic Music: She demonstrates the power to put people to sleep and send Nagasumi into Super Mode.
  • Master Swordswoman: Was trained in the Shiranui-style of kendo by Masa, and is skilled enough to match Akeno and take on the entire Edomae group by herself.
  • Megaton Punch: Her Howling Voice served this purpose during a misunderstanding in the second and fourth episodes.
  • Ms. Fanservice: Has her moments, like in episode 3 where she has a bikini for a good portion of time.
  • Nice Job Breaking It, Hero!: In the process of stopping Nagasumi's Shotgun Wedding to Lunar in episode 13, she nearly restarts the gang war between the Seto and Edomae crime families as a result. Fortunately, she and Lunar put a stop to it with a song.
  • Not So Different: As the series goes on, it's clear that Sun is very similar to her own father. She can be incredibly intimidating and loud, very possessive of Nagasumi much like her own father to her, and easily ends up as an emotional mess whenever Nagasumi shows any type of unfaithfulness.
  • One-Woman Army: In episode 13, she takes on and beats a large chunk of the Edomae group by herself.
  • Punny Name: Nagasumi sees her face superimposed on the sun.
  • Rapunzel Hair: Her hair goes past her waist and she is a yakuza princess.
  • Sarashi: When she wears her white battle kimono and when she did her delinquent roleplay outfit; an odd juxtaposition, isn't it?
  • Seashell Bra: In her first appearance where she's in full mermaid guise.
  • Serious Business: Whenever Sun busts out the rose petals and starts talking about chivalry and mermaids/honor among thieves being honor under the sea, she's entered this mode.
  • Silk Hiding Steel: Don't let her Yamato Nadeshiko personality fool you. Underneath her warm and gentle demeanor lies a rough and tough Yakuza that won't hesitate to fight for what she wants.
  • Song of Courage: One of her songs is the "Song of Heroes" which can empower Nagasumi. In the manga she also uses it on her father when he's fighting Lunar's Papa.
  • Speak Now or Forever Hold Your Peace: Sun crashes Nagasumi's wedding to Lunar dressed in a white kimono, sarashi, and carrying a katana, and announces her intent to take back her fiancé by force, even if it means renouncing her family ties and declaring war on the Edomae syndicate.
  • Spell My Name with an "S": Sun/San.
  • Testosterone Poisoning: Sun's "Sunpachi Setojima" persona consists of a "military officer" beard, tattered pants, a Badass Longcoat, sarashi, an extremely ragged Commissar Cap, and proclaiming Real Men Eat Meat - is both cringe-worthy and funny. She assumes the persona whenever she's hit by the Last Amazoness' arrows as well.
  • Verbal Tic: Tends to begin or end her sentences with "ya' see." During the arc in which the students are going to war over Sun and Lunar, the Sun faction adopts this tic as well.
    • In the English dub, her dialect can be seen as almost of a Texan influence, often dropping the "g" at the end of "-ing" words, and saying "ya'" instead of "you." (In fact, most members of the Seto gang do this.)
  • Wedding Smashers: When Lunar ropes Nagasumi into a Shotgun Wedding, Sun sinks into a Heroic BSoD before crashing the wedding wearing sarashi and a white kimono and wielding a katana, renounces her family ties, and declares war on the Edomae group in order to take back her fiancé.
  • Women Prefer Strong Men: Sun's romantic ideal is embodied in her "Sunpachi Setojima" persona, though she brushes aside Nagasumi's dejection at being the opposite.
  • Yakuza Princess: Her family operates in the Seto region.
  • Yamato Nadeshiko: While Sun may be a bit rough-spoken, she's big on honor, family tradition, and the family business, as well as being very devoted to her fiancé.
  • Zettai Ryouiki: When wearing her school uniform, she has white thigh-highs.


Mawari Zenigata
Voiced by: Rika Morinaga (Japanese), Caitlin Glass (English)

  • Baleful Polymorph: Is temporarily transformed into a mermaid after accidentally using a magic seashell meant for Nagasumi. The others pass it off as a dream once she reverts to being human, but the narration hints she kept quiet after realizing what she'd seen was supposed to be a secret.
  • The Beast Master: She can summon a horde of cats with a whistle. These are beasts in the eyes of merfolk. It's downplayed because even though she can summon them, she can't control them.
    Saru: I had no idea Mawari had gotten so good at controlling caaatttssss!
  • Catchphrase: "Must Mawari teach you the rules of this society?"
    • In the English dub, it's altered to "Maybe you need some lessons on the rules of this society!"
  • Childhood Friend Romance: She's a long-time friend of Nagasumi, and harbors a crush on him.
  • Control Freak: She's called the "Demonic" head of the Disciplinary Committee for a reason.
  • Covert Pervert: Was a bit too enthusiastic about checking out the Class Rep's three sizes in the bathhouse, and told Nagasumi she was disappointed she hadn't been able to grope Sun as well in the anime. However, she does not think Girl-on-Girl Is Hot when it's happening in a public setting.
  • Crotch-Grab Sex Check: Does this to herself after being hit by one of the Last Amazoness' arrows, and is horrified by what she finds.
  • Genki Girl: She pursues her "Sense of Justice" with great energy!
  • Heel Realization: Has one after Nagasumi gives her a broadside while she's out trying to prove Sun is, in fact, a fish. It's also aided when Sun saves her by using Howling Voice to knock aside a car that almost creams her. For the most part, she calms down around Sun after this point.
  • Heterosexual Life-Partners: With Class Rep.
  • I Want My Beloved to Be Happy: Mawari is implied to have a crush on Nagasumi for a long time, but seeing that he and Sun are happy together, she more or less sighs, puts on a smile and gets on with her life.
  • Lawful Stupid: Played for laughs. Due to her desire to be a "good cop", she tries to be Lawful Good, but due to her overzealousness, she veers towards this instead.
  • Named After Somebody Famous: She shares her name with Inspector Zenigata of the Lupin III series.
  • Secret Secret-Keeper: It's strongly implied she knows the truth about Sun and the merfolk world, but chooses to keep quiet about it.
  • Sympathetic Inspector Antagonist: Friends with the other characters, but summoning cats, when the mermaids are terrified of them, makes her an antagonist sometimes. She's not an actual police official, because she's too young, but plans to become one when she grows up. She gets bonus points for sharing a name with the former Trope Namer.
  • Teens Are Short: Despite her reputation as a disciplinarian, most offenders don't take her seriously because she's only 148cm tall. A fact which she's sensitive about and vehemently insists she's due for a growth spurt any day now.
  • Third-Person Person: Refers to herself in the third person when shouting her Catchphrase.

Hideyoshi Sarutobi (Saru/Chimp)
Voiced by: Masahito Yabe (Japanese), Anthony Bowling (English)

  • Ambiguously Bi: The end of the manga has narration saying that he and Kai "realize something" as he's rubbing sun tan lotion on Kai's back, with the hint being that they have romantic feelings for each other.
  • Barehanded Blade Block: He attempts one in Episode 17 but fails.
  • Bromantic Foil: To Nagasumi, who he is best friends with, and is much more perverted.
  • Butt-Monkey: Is the victim of slapstick violence even more than Nagasumi.
  • Crouching Moron, Hidden Badass: Dishes out a fair few pearls of wisdom, in particular when he's in his "Hermit" mode.
  • Expy: Of Hideyoshi from The Law of Ueki, they even share the same given name.
  • The Friend Nobody Likes: Most of the people he hangs out with, including his alleged best friend Nagasumi, treat him with disdain due to his selfish and perverted nature. Kai is the sole exception.
  • Heterosexual Life-Partners: With Kai.
  • High-Pressure Emotion: Steam erupts from his nose while he's drooling over Akeno in episode 16.
  • Hotblooded Sideburns: In a perverted fashion. Mostly they just make him look like a monkey.
  • Hypercompetent Sidekick: For Kai. Interestingly, he gains hypercompetence by becoming Kai's sidekick. Otherwise he's just a perverted monkey.
  • I Fight for the Strongest Side: Tried to betray Kai for Akeno, because she is hot and tougher than Kai. He returns to Kai's service when Akeno kicks him to the curb.
  • Keet: He's a hyperactive little monkey.
  • Lovable Sex Maniac: Keeps trying to persuade Nagasumi to peek on the girls changing/bathing, and is referred to as "Ero Roshi" on occasion.
  • Offscreen Teleportation: Vanishes whenever trouble shows up. He is later shown to have Flash Step-levels of speed whenever Kai requires his presence.
  • A Storm Is Coming: Plays this trope to perfection in Episode 8 in his 'hermit' mode when predicting a battle.
  • Too Kinky to Torture: Chimp's one concern above all others is sex and anything relating to it. This proves itself doubly so when Akeno attempts to crush him with her foot to get him away from her and his only response is, "Oh, yeah! I've been naughty; I deserve to be punished!"

Lunar Edomae
Voiced by: Sakura Nogawa (Japanese), Cherami Leigh (English)

  • Always Second Best: Feels this way about herself in comparison to Sun because Sun always beat her in singing contests growing up.
  • Ambiguously Bi: In the manga her Love Epiphany regarding Nagasumi extends to her rival Sun, with Lunar thinking that she wants to be with both of them forever, and chapter 39 reiterates that they are of equal importance to her. Whether these feelings are platonic or romantic is never delved into, although Saturn certainly suspects the latter.
  • Bitch in Sheep's Clothing: Her stage persona is kawaiiko to appeal to fans. If you dig beneath that she's a Jerkass, but if you dig beneath that (as Sun, Nagasumi, and Nagasumi's mom did) she's sweet again.
  • Boobs-and-Butt Pose: Is seen posing like this in her official artwork. It's promotional work after all.
  • Book Dumb: All of her tests are zeros on one occasion.
  • But Not Too Foreign: Is half-Japanese.
  • Cute and Psycho: When first introduced she flipped from being Moe to acting Ax-Crazy like a strobe light. She still has her moments, and gets this from her mother.
  • Disproportionate Retribution: She's spiteful to Sun simply because Sun always beat her in singing contests when they were kids and she's jealous of all Sun has that she lacks.
  • Friendless Background: Sun was her only friend growing up.
  • Freudian Excuse: Her mother seemingly abandoning her made her become an idol because she thinks that if she's famous enough then her mother will see her on TV and return to her. This fact, the emotional distance between her and her father, and her lack of friends also fuels her rivalry with Sun.
  • Glamour Failure: Occasionally slips out of her stage persona when at school, usually when Sun gets her riled up.
  • Green-Eyed Monster: She confesses to Nagasumi that her resentment of Sun stems from her having so much more than she does, especially a full, loving family.
  • Groin Attack: Does this to Nagasumi to "punish" him.
  • Hate Plague: Her Song of War causes uncontrollable rage and aggression in those who hear it.
  • Hates the Job, Loves the Limelight: Offstage, she can often be a pain to deal with. Onstage and/or while on camera and in public, she puts up a cutesy facade.
  • High-Pressure Emotion: When being "mistaken" for being "very fond" of Sun by her classmates, her entire face turned red and steamed.
  • Idol Singer: Number 1 in Japan. She did it to prove her superiority to Sun.
  • Inferiority Superiority Complex: She acts so egotistical to cover for how deep down she fears that she's pathetic and has nothing going for her when compared to Sun.
  • Innocent Cohabitation: Like Sun, she lives at Nagasumi's house.
  • Instant Fan Club: Deconstructed. Because she's a idol singer famous nation-wide, her fanclub was already present and organized before she transferred into Nagasumi's school.
  • It's All About Me: She thinks Sun married Nagasumi to flaunt this fact in her face, disregarding the whole 'marry into the mermaid family or die' thing.
  • I Want My Beloved to Be Happy: Partially why she ultimately accepts Nagasumi and Sun as a couple and gives up pursuing Nagasumi is that she wants Nagasumi to be happy. The other part, as she admits to herself, is that she also wants Sun to be happy.
  • Jerk with a Heart of Gold: She acts haughty and abrasive to everyone but there's a Nice Girl underneath it all.
  • Love Epiphany: At first Lunar was going to marry Nagasumi solely because she was "stealing" him away from Sun, but after Nagasumi gives a passionate speech to her dad she seems to genuinely fall for him. In the manga, the epiphany actually extends to Sun as well.
  • Mafia Princess: Her dad is the head of the Edomae gang.
  • Magic Music: Her favorite is the "Song of War", which turns its audience into mindless warriors. She learned it from her mother as a lullaby.
  • Missing Mom: According to her father, Lunar's mom ran away from her family. Chapter 66 reveals, 10 years prior, Lunar's mom got sentenced to prison for attempting to run over Lunar Papa (among other charges) for being more attentive to the company than his family. She was offered a completely waived sentence but refused out of spite. In the process, she also divorced him.
  • Mistaken for Gay: Saturn hates Lunar just as much as she hates Nagasumi because she believes Lunar wants Sun.
  • Mistress and Servant Boy: She tries to force Nagasumi into one of these relationships. She insists on calling him "manservant" rather than his given name.
  • My God, What Have I Done?: After Lunar exploits her father walking in on Nagasumi rubbing her naked butt to rope him in to a Shotgun Wedding, she inwardly berates herself for being so cruel to Sun after seeing how despondent she is, even though her own ego causes her to rub the incident in Sun's face.
  • Noblewoman's Laugh: A habit of hers when not using her façade as a cutesy idol, and lampshaded by other characters.
  • Ojou: From her dad's status and her own as a pop star she's treated like nobility.
  • Royal "We": The only time she ever speaks in the singular is when Nagasumi teaches her a lesson in humility.
  • Spell My Name with an "S": Lunar/Luna/Runa. Luna is her real name, and Lunar is her stage name.
  • Tsundere: Mellows in the second half of the series into this, for both Nagasumi and Sun. For the former, she'll openly flirt with but violently deny actually liking him. For the latter we have this gem:
    —"We rearranged our schedule to see you, but don't get the wrong idea! It's not because we wanted to have fun with you!"
  • Unknown Rival: For Sun, who thinks they're best friends. They're Vitriolic Best Buds later in the series.
  • Vitriolic Best Buds: With Sun, the vitriol coming mostly from Lunar. For all her claims of hate it eventually becomes clear that Sun is very important to her.
  • Yandere: Behaves like one early on. How much it was for Nagasumi's love and how much was to one-up Sun is open for debate but she certainly had extreme measures.
  • Zettai Ryouiki: Hers are black for the added contrast to Sun's white.

Class President/Chiyo Iin
Voiced by: Noriko Rikimaru (Japanese), Kate Bristol (English)

  • Beautiful All Along: Before and after. The difference in her appearance is amazing, is it not?
  • Blind Without 'Em: She spent a day with Nagasumi and didn't realize it because she didn't have her glasses.
  • Butt-Monkey: Out of all the girls in Nagasumi's Unwanted Harem, she's definitely the unluckiest.
  • Catchphrase: "Yes! Amazoness!" as the Last Amazoness.
  • Class Representative: Everyone thinks this is her name because it is her role in class.
  • Covert Pervert: When she says Nagasumi has become more manly (episode 15), the two incidents she cites involve him being naked.
  • Dropped Glasses: In episode 15, she loses her glasses when Nagasumi accidentally steps on them.
  • Energy Bow: As the Last Amazoness she has a bow that fires magical Gender Bender energy arrows.
  • Everyone Calls Him "Barkeep":
    • She is never referred to by her real name (much as she wants to be), only 'Iincho'.
    • Her real name is finally revealed in volume 16, and it is 'Iin Chiyo'. When written in hiragana, her name can be read as 'Iincho'.
  • Faux Yay: The Class President pretends to be a lesbian to overcome her shyness.
  • Heterosexual Life-Partners: With Mawari.
  • Hopeless Suitor: To Nagasumi, who only has eyes for Sun. Made worse, since he doesn't even know their class rep's name, or that she's even interested in him.
  • Meganekko: Inverted in that her glasses hide her attractiveness rather than produce it.
  • Mistaken for Gay: After accidentally confessing to Sun with her hair down and glasses off, she is forced to adopt the "Last Amazoness" persona to cope.
  • Ms. Fanservice: Tries to be this during the sports festival, and is put off when Lunar out-sexies her.
  • Not Evil, Just Misunderstood: Despite being portrayed as the enemy of all men as the Last Amazoness, all she wants is to be able to confess to Nagasumi.
  • Shrinking Violet: Painfully shy, and to make it worse, the one time she built the courage to overcome it, she ended up confessing her love to Sun by accident.
  • Transformation Sequence: Near the end of episode 21 into the "Last Amazoness".

Kai Mikawa
Voiced by: Daisuke Ono (Japanese), Eric Vale (English)

  • Always Someone Better: Compared to Nagasumi, he's rich, handsome and childhood friends with Sun. Despite this, however, he rarely ever poses much of a threat to him.
  • Ambiguously Bi: The end of the manga has narration saying that he and Chimp "realize something" as Chimp is rubbing sun tan lotion on his back, with the hint being that they have romantic feelings for each other.
  • Bishōnen: Noted to be very good looking.
  • Butt-Monkey: Being a severely agoraphobic whaleman who is also an uncontrollable Large Ham will do that to you.
  • Chick Magnet: Every unnamed girl at Nagasumi's school is in love with him. It helps that he's loaded.
  • Cool Sword: One with a long history, but he doesn't get to use it until the anime's climax.
  • Crouching Moron, Hidden Badass: He's a Master Swordsman once he gets past his agoraphobia.
  • Custom Uniform: His outfit resembles a navy admiral's uniform.
  • Entitled Bastard: Being rich, he thinks he's owed the best of everything. In Episode 24, it takes him a while to find out that everyone's treating him super nicely because they think he's dying of a terminal illness; he just assumes that they finally wised up and are treating him the way he "deserves" to be treated.
  • Expy: Clearly meant to be a parody of Shuutarou Mendou from Urusei Yatsura, with the latter's crippling claustrophobia inverted into crippling agoraphobia.
  • Green-Eyed Monster: Jealous of Nagasumi due to his ability to find genuine love and friendship in others while he has to buy it with his money.
  • Friendless Background: Much like Lunar, Sun was the only one he had in his childhood that he considered a true friend.
  • Heterosexual Life-Partners: With Saru.
  • Hikikomori: After a traumatic experience in a vast desert when he was young, he has developed a severe case of agoraphobia and never truly went outdoors until transferring to Nagasumi's class. He's described as a "submarine hikikomori" in his joint Image Song with Saru.
  • Instant Fanclub: All of the unimportant girls flock to him the moment he appears.
  • Jerkass Realization: He has one in Episode 24 when, while thinking he's dying of a terminal illness, he realizes how much the people around him cared for him and how he took that for granted. It comedically becomes an Ignored Epiphany after it's learned he wasn't ill after all and the status quo reasserts itself.
  • Jerk with a Heart of Gold: He's not so bad once you get past his obnoxiousness. He and Nagasumi actually tend to get along well when they're not fighting.
  • Large Ham: When he's not proudly shoving his wealth in your face he's screaming about his fear of the outdoors.
  • Lonely Rich Kid: He's in love with Sun because she didn't care about money or status. That and she played a weird version of house with him.
  • Mistaken for Dying: In Episode 24 everyone thinks he's terminally ill, and it gets to the point where Mikawa himself thinks he's dying.
  • Murder the Hypotenuse: He has no qualms attempting to kill Nagasusmi if the opportunity presents itself, although by the end of the series this has stopped happening and he respects Nagasumi as a Worthy Opponent.
  • Real Men Wear Pink: He's a fan of romance movies.
  • Rich Bastard: He uses money to solve his problems. Sun calls him out on this in his debut episode and he gets a little better about it.
  • The Rival: Set up as this to Nagasumi. The anime tends to zig-zag on whether or not it sticks.
  • Screw the Rules, I Have Money!: Again, in his first episode he threw money around to get what he wanted. Then Sun told him off for it. He's better about it later on.
  • Shonen Hair: It's big and spiky.
  • Used to Be a Sweet Kid: When he was young, he was upset that people only spent time with him because of his money and came off as quite nice. In the present, he fully accepts that the only reason other people want to spend time with him is because he's rich and he regularly throws around huge sums of money as a result. Later episodes reveal that this resentment of his wealth is still buried under the surface.
  • Worthy Opponent: Comes to respect Nagasumi as one. Nagasumi generally just sees him as a weirdo.

Akeno Shiranui
Voiced by: Eri Kitamura (Japanese), Trina Nishimura (English)

  • Action Girl: Cold, driven and very good with a sword.
  • Adaptational Villainy: While in the manga she was a Hero Antagonist/Anti-Villain due to being ordered by the government to break up Sun and Nagasumi, in the anime she's revealed to be The Dragon to a corrupt, lecherous noble who wants to abduct Sun. However, she turns on said noble when she realizes this.
  • All Amazons Want Hercules: Implied to prefer men who are stronger warriors than herself via a love potion Ren gave Nagasumi. While under its influence, Akeno sees Nagasumi as a martial artist with such an impenetrable defense that she immediately concedes without a fight by casting down her sword. Then blushes and says he can do as he wishes with her.
  • Anti-Villain: Type 5. While she is a antagonist to the main pair, if she didn't do her job there would be more problems for everyone.
  • Best Her to Bed Her: Heavily implied during the aforementioned love potion incident. The moment Akeno drops her sword, she unfastens her hair and blushes as she offers herself to Nagasumi.
    Akeno: (aroused) "I concede to you. Do as you wish."
  • Big Brother Worship: Adored her older brother as a child and wants to be like him... but hates him for disgracing their family with his disappearance and one of her secondary missions is to execute him if she finds him.
  • Big Eater: Akeno has a surprisingly ravenous appetite. She can down entire buckets of rice and still have room for more.
  • Boobs of Steel: Not only does she excel in swordsmanship, but she's also the bustiest of the main cast.
  • Buxom Is Better: According to Saru, Akeno is even bustier than Sun, and she become the centre of attention in Episode 17 for this reason. Even Mawari, Gozaburo, and Fujishiro think she's "vexingly sexy".
  • Catchphrase: "How vexing."
  • Defector from Decadence: When she discovers that Yoshiuo only wanted her to break up Sun and Nagasumi so he could have his way with Sun, she turns on him.
  • Even the Girls Want Her: Mawari and a few other girls in the class call her "vexingly sexy" out of jealousy for her figure. Taken a step further in the manga with Jupiter.
  • Evil All Along: In the anime's final arc it's revealed she was working for a lecherous merman noble who has his eyes on Sun. Subverted in that she was unaware of said noble's true intentions, and pulls a Heel–Face Turn when she learns them.
  • Gainaxing: While playing sports in Episode 17 and at the pool in Chapter 60, making her (and Sun in the latter case) the centre of attention.
  • Heel–Face Turn: She was a villain starting out with her mermaid exam but switches to Nagasumi's side in the anime's climax.
  • Heel Realization: After hearing 1/8th Figurine's warnings regarding Minamoto no Yoshiuo, she starts questioning the government's reasons for being so desperate to break up Nagasumi and Sun, and realizes she was Yoshiuo's Unwitting Pawn.
  • Hot Teacher: In the military academy she was a combat instructor for a short while, and schooled Maki Yuri.
  • In-Series Nickname: She has such stern and unyielding presence that even the toughest delinquents at the school are intimidated by her. But they're equally awed by her beauty and sex appeal, so they refer to her as the "Vexingly Sexy Shotcaller". It doesn't take long for it to spread around campus, 'til everyone begins to address by her new title.
  • Mistaken for Gay: Mawari has had this impression of Akeno ever since overhearing her attempts to increase Sun's endurance to water and walking in on them in a compromising position. The appearance of Jupiter helped this misconception. Saturn also has this perception of her and sees her as a threat to her and Sun being together.
  • My God, What Have I Done?: Has this moment in the anime's finale, prompting her Heel–Face Turn. In the manga she has another moment after confessing to Nagasumi, feeling she betrayed Sun's friendship, and later still when she realizes the truth behind the government order to break up Sun and Nagasumi.
  • Named After Someone Famous: She shares her last name with Mai Shiranui, who's also a martial artist and a ponytailed, large breasted kunoichi from both the Fatal Fury and King of Fighters series.
  • Phrase Catcher: She's referred to multiple times as "vexingly sexy" for an episode.
  • Punch-Clock Villain: She's not evil, but she takes her job very seriously.
  • Sarashi: Wears this instead of the bib in her school uniform, emphasizing her status as a skilled swordswoman.
  • Situational Sexuality: Had a Schoolgirl Lesbians relationship with Jupiter during their time at the military academy.
  • To Be Lawful or Good: As a trainee swordsman she has to obey nobles but as a good person she has to disobey one. She choose to be good.
  • Tsurime Eyes: It highlights her aggressive personality.
  • Why Did It Have to Be Snakes?: Despite being a badass swordswoman with skills on par with Sun's, she is terrified of ghosts.
  • Wrecked Weapon: Maki Yuri slices her sword to pieces in the manga's final arc.

     Seto Clan 

  • Badass Crew: They're all superpowered mermaid gangsters.
  • Card-Carrying Villain: Again, gangsters and proudly so.
  • Honor Among Thieves: They have their own code of honor. In the first episode, Sun tells Gozaburo that killing someone for no reason is just as bad as breaking The Masquerade according to the mob code, and in episode 14, Maki saves the kitten from drowning because it saved her from being trampled, saying that she always pays back what she owes.
  • The Pirates Who Don't Do Anything: The most evil thing they do is hassle Nagasumi.

Gozaburo Seto
Voiced by: Kenta Miyake (Japanese), John Swasey (English)

  • Amazingly Embarrassing Parent: On one occasion, Gozaburo dresses up like a Cat Girl in an attempt to better understand Sun. Unsurprisingly, Sun has to literally be dragged kicking and screaming to school that day.
  • Berserk Button: Flies into a rage whenever he sees Nagasumi and Sun doing anything remotely romantic.
    • In the anime, this extends to anyone threatening his Sun.
  • Bunny-Ears Lawyer: He's the influential leader of an enormous mob of undersea gangsters, but spends most of his screen time acting as Sun's Bumbling Dad.
  • Even Evil Has Loved Ones: For all of his faults, he does deeply love and care about his daughter.
  • Good Scars, Evil Scars: On his face. The good kind over the nose.
  • Hair-Trigger Temper: It doesn't take much to set him off, especially is Nagasumi's involved.
  • Henpecked Husband: It becomes painfully clear in a few episodes that it is Ren who is the true ruler of the Seto Yakuza clan, not Gozaburo.
  • Knight Templar Parent: He inflitrates Nagasumi's school and frequently sends assassins out of a misguided attempt to protect his daughter.
  • Large Ham: He tends to Chew the Scenery in almost every scene he's in.
  • Love-Obstructing Parents: Gozaburo sends assassins to prevent intimacy between his beloved daughter and "that snot" Nagasumi, while Ren tries to keep her husband under control.
  • Obnoxious In-Laws: He makes it clear he absolutely despises his son-in-law and repeatedly attempts to kill him.
  • Overprotective Dad: He is overprotective to the point of homicidal mania when his daughter gets married. He repeatedly attempts to kill his son-in-law, and eventually takes over Nagasumi's school, replacing the staff with his enforcers so he can better keep an eye on his daughter. Hilarity Ensues.
  • Papa Wolf: As much as he tries to kill or at least hurt Nagasumi (all of which are always Played for Laughs), he will protect him and Sun if they are genuinely threatened, such as when Sun is kidnapped, or when Lunar's dad first shows up at school.
  • Psychopathic Manchild: While he's the boss of the Seto Clan and threatens Nagasumi, his wife still sees him as a spoiled, immature brat who never left middle school and it shows.
  • Tears of Blood: When Sun decided to live with Nagasumi he took it poorly.
  • Villainous Breakdown: Whenever Sun does something especially drastic, like deciding to marry a human, cut ties with her family and declare a one-woman war on the Edomae Outfit, or cross-dress as a delinquent, poor "Go-chan" is reduced to a sobbing, blabbering wreck.
  • Why Did It Have to Be Snakes?: He still has a fear of cats because of an incident in his childhood where a cat bit his ear while he was sleeping and he nearly lost it due to the resulting infection.

Ren Seto
Voiced by: Makiko Nabei (Japanese), Stephanie Young (English)

  • Affably Evil: With how nice and mild-tempered she is, she's only "evil" because she's a yakuza head.
  • Berserk Button: Her husband's chronic immaturity and over-possessiveness regarding their daughter never fails to irritate her.
  • Beware the Nice Ones: Is genuinely sweet and fairly even-tempered, but make her angry and she will break you.
  • Carnivore Confusion: Offers Masa some fried octopus tentacle at the Bon Festival, and when he inquires whether it belongs to Nakajimanote ; she shrugs and takes a bite out of it, to his horror.
  • Cherry Blossoms: When she wants to be dramatic, she makes these petals fall when giving a speech.
  • Happily Married: Despite how much Gozaburo's antics anger her she really does love him. Case in point: Nagasumi once drank a potion that makes him appear to females as whatever they think is "extremely sexy" and Ren's version of him looks almost identical to Gozaburo.
  • Kimono Is Traditional: Regularly wearing a purple kimono (when not working as the school nurse) presumably as a clan tradition thing.
  • Let Her Grow Up, Dear: In contrast to her husband she is a Shipper on Deck for her daughter and Nagasumi. She's very happy every time the intimacy in their relationship seems to go up a notch. If only they moved beyond hugging and hand holding.
  • Loophole Abuse: She was the one who got Nagasumi and Sun engaged to prevent one of them from being Killed to Uphold the Masquerade, because humans who marry into a merfolk family are the exception to the rule.
  • Marshmallow Hell: Inflicts this on Nagasumi to tease him.
  • Only Sane Woman: The most level-headed and reasonable member of the Seto Clan, besides Masa.
  • Reasonable Authority Figure: Whereas her husband is Hot-Blooded most of the time, Ren is generally calm and collected, and doesn't make rash decisions as her husband tends to do. She and her husband also pay to repair the damage caused to Nagasumi's house as a result of his or Maki's usual overreactions there.
  • School Nurse: Her excuse to infiltrate the school. Nagasumi goes there whenever he needs a calm moment or gets injured,
  • Shipper on Deck: She supports Nagasumi and Sun, and is usually the one to punish Gozaburo whenever he tries to interfere in their relationship.
  • The Tease: Her favorite target is Nagasumi; yes, her daughter's fiancé whom she ships. It's all in good fun.
  • Token Good Teammate: Along with Masa, she's the only member of the Seto outfit who supports Nagasumi's relationship with Sun and doesn't actively try to kill him.
  • Ugly Guy, Hot Wife: Ren is shown to be a babe with a bangin' hot bod, especially whenever she's in her nurse's uniform. So it's a wonder how Gozaburo managed to hook up with her, given his face is horribly scarred.

Masa Shiranui
Voiced by: Katsuki Murase/Shuichi Ikeda (Japanese), Christopher Sabat (English)

  • The Ace: Cool, smart, strong and loved by everyone, Masa parodies this because it is played for laughs.
  • Badass in a Nice Suit: A gangster swordsman who dresses very well.
  • Badass Teacher: Works as a math teacher at Nagasumi's school to keep tabs on Sun and the lessons tend to involve gangster mechanics.
  • Berserk Button: Do not make his little sister cry.
  • Big Brother Mentor: A frequent source of wisdom to Nagasumi and occasionally other characters. Nagasumi also has a pretty noticeable man crush on him.
  • Characterization Marches On: Before suffering from amnesia caused by Gozaburo Seto, Masa used to act and look completely different, being an easygoing brother of Akeno and looked similar to her.
  • Cool Shades: One more reason why Nagasumi thinks he's the coolest person ever.
  • Death Glare: Gives one to Maki Yuri for making his little sister cry.
  • Even the Guys Want Him: Masa-san is a sexy beast.
  • Funny Afro: Averted. He has an afro but he's never comic relief.
  • Identity Amnesia: Forgets his real identity after a drunken Gozaburo punched him in the head.
  • Long-Lost Relative: He is actually Akeno's older brother.
  • Master Swordsman: He was the one who taught Sun the Shiranui-style of kendo.
  • Only Sane Man: He's calm, cool and competent in almost all situations.
  • Red Baron: When he was a government agent he was known as Myoujyou of the Thousand Blades.
  • Sacred First Kiss: To Nagasumi (Played for Laughs constantly in the anime) because of a Kiss of Life situation.
  • Soul Brotha: Dark skin, huge afro, and virtually every other character sees him as a cool guy. Odd, as he used to look completely different, with pale skin and long straight hair.
  • Spike Shooter: His special technique, White Fish Scales, allows him to create giant bladed scales from any solid matter.
  • The Stoic: Does not have many facial expressions compared to other characters and hardly changes his tone when speaking, regardless of the situation.
  • Token Good Teammate: Aside from Ren, he's the only person in the gang that doesn't actively try to harm Nagasumi.

Voiced by: Natsuko Kuwatani (Japanese), Monica Rial (English)

  • Affectionate Nickname: Calls Nagasumi "Sea Louse" originally as an insult, though as she's thawed towards him it's become somewhat more affectionate.
  • Beware the Nice Ones: Because, in this case, they're only pretending to be nice.
  • Bitch in Sheep's Clothing: Acts like a Shrinking Violet for Sun, but in reality, she's a crude and violent assassin who constantly tries to kill Nagasumi all while keeping up the charade so Sun doesn't suspect anything.
  • Cain and Abel: She has a younger sister, Fuki, who lives in Hokkaido, and was the Cain to her when they were children; nowadays, Fuki is just as rude and bitchy as Maki herself.
  • Glamour Failure: Her Humanization Transformation is imperfect, making her mouse-sized. She later perfects it and becomes able to transform into a human properly.
  • Hopeless Suitor: Becomes a member of Nagasumi's Unwanted Harem in an effort to break him and Sun up, although it's hinted she may have developed genuine feelings for him.
  • Jerk with a Heart of Gold: For all of her faults, Maki deeply cares for Sun and Gozaburo and is loyal to them no matter what.
  • Licked by the Dog: Kitten, in this case. A kitten that Nagasumi adopts in Episode 12 takes a liking to her and keeps licking her, much to her disgust.
  • Killer Rabbit: A cutesy little girl who's literally small enough to fit in the palm of a human hand. Do not underestimate her.
  • Little Miss Badass: Literally; being knee-high to a pencil doesn't stop her from being a yakuza assassin.
  • The Only One Allowed to Defeat You: Uses this as her excuse for protecting Nagasumi from Yoshiuo's eel in Chapter 29.
  • Our Fairies Are Different: When the Class Rep sees her moving, Maki pretends to be a fairy. It works, but bites her in the ass at the same time.
  • Parrot Pet Position: She's often shown sitting on either Sun or Masa's shoulder. Justified since she's small enough to easily do so.
  • Pet the Dog: In the anime she saves the kitten from drowning despite being terrified of it, in return for it saving her from being trampled. She also expresses begrudging respect and even on rare occasions sympathy towards Nagasumi. In episode 22, she also ends up bonding with Lunar and pledging to help her out, and in the manga she even displays some decency toward Class Rep.
  • Poisonous Friend: For Sun. If Maki has her way, the poor girl will never have a healthy romantic relationship (for her own good, of course).
  • Shout-Out: She has a visor and a 'surfing ram' attack. Hi there, Temjin.
  • Size Shifting: Late in the manga she perfects her Humanization Transformation, allowing her to grow to the size of a normal human in order to seduce Nagasumi away from Sun.
  • Small Girl, Big Gun: It's tiny by human standards, but massive compared to her and possesses heavy-duty firepower.
  • "The Reason You Suck" Speech: Delivers one to Lunar while posing as her "Chibi Lunar" hand puppet, lampshading how transparent Lunar's Bitch in Sheep's Clothing routine really is.
  • Tsundere: In the latter parts of the manga, she acts heavily Type A way towards Nagasumi, though whether she actually has feelings for him or it's just another ploy to break him and Sun up is unknown.
  • Undying Loyalty: To Sun and Gozaburo, her charge and her boss, can rest assured of her faithfulness.
  • Verbal Tic: desu~ when pretending to be cutesy.
  • What the Hell, Hero?: Calls Lunar out on her cruelty to Sun during the Edomae Shotgun Wedding arc, even though she could have just as easily dispelled the misunderstanding herself.
  • Why Did It Have to Be Snakes?: Like most mermaids, she's scared to death of cats. Unfortunately for her, the kitten Nagasumi adopts takes a liking to her, even pouncing on her and licking her face.
  • Worthy Opponent: Reluctantly comes to see Nagasumi as such, though she'd never admit it.
  • Yandere: She has Undying Loyalty for Sun and will do anything to protect her up to, and including, murdering her husband for some preceived slight.
  • You Gotta Have Blue Hair: She has purple hair.

Shark Fujishiro
Voiced by: Takehito Koyasu (Japanese), Bryan Massey (English)

  • Badass Teacher: Works as the gym teacher at Nagasumi's school to keep tabs on Sun and tries to eat him outside of class.
  • Catchphrase: "Can I eat him/her/them?"
  • The Dreaded: Nagasumi is terrified of him, and for good reason. On one occasion, Nagasumi thinks to himself that Fujishiro may be even more dangerous than Gozaburo himself.
  • Everything's Even Worse with Sharks: For Nagasumi, yes. His appearance signals a bout of running for his life.
  • Goofy Print Underwear: With little fishies on them.
  • Gory Discretion Shot: The one time Fujishiro does get to eat something in the anime, namely Yoshiuo's mooks, all that's seen of it is him shouting "Thanks for the meal!", the horrified expressions of Akeno and the other onlookers in the background... and enough blood painting the foreground to match the goriest of slasher flicks.
  • Hair-Trigger Temper: It doesn't take much to piss him off.
  • Heroic Comedic Sociopath: Nearly all his scenes involve him trying to eat Nagasumi or asking if he can eat the other students. This would make him a villain if he weren't (technically) allied to Nagasumi against people like Lunar Papa and if his antics weren't played for laughs.
  • Mistaken for Pedophile: When he, Masa, and Gozaburo are caught conspiring against Akeno by Ren, they come up with lame excuses based on her figure. Fujishiro remarks that he would "eat her in more than one way", causing Masa to comment on how wrong that sounds. Later, when he asks Mawari if he can "eat" her, she accuses him of sexual harassment.
  • Murder Is the Best Solution: His typical approach to solving a problem is to try to eat the source of said problem.
  • The Only One Allowed to Defeat You: No one else may eat Nagasumi.
  • Partial Transformation: Reverts just his head back to shark form when on land.
  • Scary Teeth: Even in human form he has sharp teeth.
  • Strange-Syntax Speaker: He speaks as if all sentences were questions.

Octopus Nakajima
  • An Arm and a Leg: Ever since the Bon Festival, when Ren cut off and ate one of his limbs, he's been losing tentacles. At one point he even used his own tentacles in home ec. class.
  • Combat Tentacles: Though they're not very effective considering everyone keeps cutting them off and cooking them.
  • Curb-Stomp Battle: He loses easily against an enlarged Nagasumi.
  • Glamour Failure: He's apparently the home ec teacher, but hasn't perfected his Humanization Transformation and randomly reverts back into octopus form.
  • Kaiju: He's a giant pink octopus.
  • Unusually Uninteresting Sight: He's usually seen sticking out of a window in octopus form when at school. Apparently this hasn't harmed the masquerade at all.

Maguro, Agitaro & Furiyo

Maguro is voiced by: Kouki Harasawa (Japanese), Chris Cason (English)
Agitaro is voiced by: Keisuke Fujii (Japanese), Josh Grelle (English)
Furiyo is voiced by:Atsushi Imaruoka (Japanese), Sonny Strait (English)
  • Elite Mook: They are supposedly three of Gozaburo's best agents. Supposedly.
  • Glamour Failure: Their Humanization Transformations were incomplete, leaving them with fishlike faces, and they have no resistance to water whatsoever.
  • Goldfish Poop Gang: And a rather literal example too, seeing as they're part fish!
  • Gonk: Their faces are distinctively fishy.
  • Heel–Face Revolving Door: They've deserted the Seto Outfit to work for Akeno and Jupiter, but are always Easily Forgiven.
  • Informed Ability: They're stated to be Gozaburo's Elite Mooks, but, like most merpeople, are scared witless of cats. On top of that, they're easily curb-stomped by Akeno in episode 16 not once, but twice.
  • Paper-Thin Disguise: One of them crossdresses in order to disguise himself and get close enough to deal with Nagasumi's cat. Unfortunately, everyone involved sees through it immediately, because it's kind of hard to disguise yourself when you look like this.
  • Those Two Guys: A cast herd of three minor characters whom no one remembers.
  • Verbal Tic: All three of them have the exact same one, gyo!

     Other Characters 

Lunar's Papa
Voiced by: Tessho Genda (Japanese), J. Michael Tatum (English)

  • Action Hero: As part of his The Ahnold trope, he acts like this on occasion; his introductory scenes involve jumping out of his car from the highway and dodging explosions. He is also quite a capable fighter, as seen by his battle with Sun's father at school.
  • Adaptational Villainy: In his manga debut, he actually just wants to talk to Nagasumi about Lunar and is mistaken for trying to attack him due to how forceful he comes off. In the anime, there is no such misunderstanding: he actually is trying to attack Nagasumi.
  • The Ahnold: A blatant Terminator expy and has the accent.
  • Amazingly Embarrassing Parents: Lunar is repeatedly embarrassed by her father's efforts to get closer to her, particularly whenever he cross-dresses with a Sailor Fuku.
  • Barehanded Blade Block: He catches Kai's sword in two of his fingers then snaps it.
  • Brain Bleach: Him wearing a Sailor Fuku is this for his daughter and many others. (shudder)
  • Captain Ersatz: Of the Terminator. One can assume the only reason that nobody was sued is because he is played for laughs.
  • Cool Shades: His sunglasses hide his eyes and make him all the more like a robot.
  • Doting Parent: He tries to be a good father. Now if only Lunar would stop pushing him away whenever he tries to reach out...
  • Everyone Calls Him "Barkeep": He is only referred to as Lunar's papa.
  • Eye Beams: Seen firing them in the finale like a robot would.
  • Gratuitous English: In Terminator shoutouts no less!
  • Implacable Man: His introductory episode is played like a (comical) horror movie with an unstoppable monster chasing The Protagonist.
  • Lawyer-Friendly Cameo: He's is a blatant Terminator ripoff and if he weren't played for laughs (among other things) the writers might have been sued.
  • Made of Iron: Not even a Kill Sat can stop him. His first appearance is even called "Iron Man".
  • Moe: In-universe example. In his continuing efforts to relate to Lunar, he studied gal games and learned about archetypes such as the Childhood-Friend and Little-Sister.
  • No Social Skills: He doesn't know how to communicate with people very well outside of scaring the crap out of them (especially his own daughter).
  • Real Men Wear Pink: This guy is so ripped and scary that not even wearing a sailor fuku makes him any less manly.
  • Reasonable Authority Figure: He can be this at times, such as when Lunar needed some extra money to finish shooting a film. He shows up in a helicopter and drops a large suitcase of cash to help her finish it. Also, like Sun's father, he also pays for repairs to Nagasumi's house anytime he wrecks it.
  • Retired Outlaw: Wanted to go straight after Lunar was born, but his wife took issue with him putting the company in front of his family.
  • The Stoic: The reason he's thought to be a robot is because he shows so little emotion. This is a sticking-point in his relationship with both his wife and his daughter; despite how much he loves them he has difficulty expressing it.
  • Terminator Impersonator: Takes the Terminator aspect and plays it for as many laughs as possible. Both English and Japanese dubs give him Schwarzenegger-like mannerisms; he's never seen without his black shades; he relentlessly hunts down Nagasumi in his own school while causing a panic among the students; he's completely unfazed when Nagasumi hits him with a Kill Sat; and in his introductory episode, he makes his exit by climbing into a dumpster fire and slowly lowing himself down into it while giving a thumb's up.

Nagasumi's Family

Nagasumi's father is voiced by: Atsushi Imaruoka (Japanese), Andy Mullins (English)
Nagasumi's mother is voiced by: Noriko Namiki (Japanese), Lydia Mackay (English)
Nagasumi's grandmother is voiced by: Eriko Matsushima (Japanese), Juli Erickson (English)

  • Abusive Parents: They have No Sympathy for the various problems Nagasumi faces, wish that he was a girl and would rather have Sun as a child, and have absolutely zero qualms about declaring him to be a worthless disgrace to their family, even when he's standing right in front of him.
  • Adults Are Useless: Whenever there's a problem, they quiver in a corner.
  • Cool Old Lady: Unlike Nagasumi's parents, his grandma remained totally calm at Sun's sudden visit and marriage proposal. She is much more reasonable towards Nagasumi than his parents are and even gave him a generous amount of money so that he can enjoy the summer festival together with Sun (specifically so he could buy Sun whatever she wanted).
  • Henpecked Husband: Mrs. pushes Mr. further and further away from the family as the series progresses. Soon, he's no longer at the dinner table.
  • Hidden Badass: Nagasumi's Mom taught Mawari how to play karuta, and has skills and reflexes that vastly exceed even Akeno's.
  • No Sympathy: Nagasumi's parents' typical reaction to any of his many, many problems is to ignore them.
  • Unnamed Parents: They are not named and are only known as Nagasumi's family.
  • Wanted a Son Instead: At many points they say they'd rather have a daughter than a son. Mrs. just loves washing dishes with her daughter-in-law.
  • Why Are You Not My Son?: Nagasumi's parents consider him a loser, and declare Sun, Lunar, and Maki to be the daughters they wish they had. To the point that they move their son to the attic and move Sun to his room.

Minamoto no Yoshiuo

Voiced by: Daisuke Namikawa (Japanese), Chris Patton (English)

  • Adaptation Expansion: His portrayal in the anime differs from his portrayal in the manga. At least at first.
  • Adaptational Villainy: He is much more vile in the anime than in the manga, being an outright rapist who also attempts to murder Sun when she defies him as opposed to just an evil, power-hungry aristocrat. His comeuppance is much more painful - and cathartic - as a result.
  • Aristocrats Are Evil: Is the main antagonist for the anime's finale, and the manga's finale as well by exploiting his noble status for selfish purposes.
  • Bad Boss: Threatens to have his way with Akeno if she doesn't obey him in the anime.
  • Big Bad: He's revealed to be one the behind Akeno in the anime's finale and fighting him is the finale. He's eventually revealed to be the Big Bad of the manga as well.
  • Crazy-Prepared: Has spies in every place even remotely related to Sun.
  • Dude, She's Like, in a Coma!: Drugs Sun into a stupor and would have raped her in the anime's finale if it hadn't been for Nagasumi.
  • Gonk: Is an anthropomorphic catfish, and even less human-looking than Maguro, Agitaro, and Furiyo. It's partially averted in the anime, where his human form is a Bishōnen man with long blue hair.
  • Harmless Villain: In Chapter 29 of the manga he invites Sun and Nagasumi into his manor only to woo the former and try to feed the latter to his pet giant eel. After Sun pleads for Nagasumi to be spared, he apologizes and pledges his support to them, but... he lied and turns out to be Not So Harmless after all.
  • Heel–Face Turn: The manga version of Yoshiuo has the evil in his heart destroyed by a magic spear and changes his ways.
  • Kaiju: Keeps an enormous eel called "Ucchan" as a pet, and has three of them in the anime.
  • Karma Houdini Warranty: He finally gets his comeuppance at the hands of Nagasumi towards the end of the series.
  • Love at First Note: Fell in love with Sun's singing voice when she was just a child.
  • Man Behind the Man: In the finales of both the anime and the manga it is revealed he was the one who issued the Merperson Examination's secret mission to break up Sun and Nagasumi.
  • Not-So-Small Role: Was seemingly a one-shot minor antagonist in the manga, but is later revealed to be the Big Bad.
  • Phoneaholic Teenager: He acts like one in the anime when he is in his human-looking form, prone to lounging around and ordering others to do work for him while he does trivial things.
  • Rape Is a Special Kind of Evil: In the anime he has a reputation of drugging and raping girls who catch his fancy, and sets his eyes on Sun. He also threatens to rape Akeno if she doesn't follow his orders. This makes him more deplorable than both the gangster assassins and the remorseless government agents.
  • Yandere: Anime version. Is fixated on having Sun for himself and drugs her for his perverse pleasure.

Akeno's Superior


Voiced by: Tomoko Kaneda (Japanese)

Sarutobi's younger sister.

  • Annoying Younger Sibling: Saru treats her as such, although she is as equally annoyed by him.
  • Precocious Crush: While she initially dismisses him, she develops one on "Nagasumi Willis" after he saves her.
  • Punny Name: In the OVA's opening she can be seen dancing the Monkey in the background.
  • Rescue Romance: Towards Nagasumi after he saves her from a collapsing theatre.


Voiced by: Ayumi Tsunematsu (Japanese)

A childhood friend of Sun, Saturn is a seaweed creature whose hair can act as weapon. She becomes an English teacher at Sun's junior high school.

  • Adaptational Nice Guy: In the sole OVA she appears in, all of her willfully negative traits are removed. Her attacking people is more of an accident done out of a skittish sense of self-defense, and she goes back to the sea on good terms with everyone at the end rather than sticking around to become a Yandere Sadist Teacher.
  • Adapted Out: Didn't appear in the anime, and only her manga debut was adapted into an OVA. Lampshaded in a preview at the end of Chapter 54.
  • Blackmail: She can use her stalking skills to blackmail just about anybody.
  • Ceiling Cling: Uses this to avoid detection and ambush targets.
  • Childhood Friend Romance: She has a blatant lesbian crush on her childhood friend Sun.
  • Clingy Jealous Girl: She becomes extremely jealous of people close to Sun and hates Nagasumi, Lunar and Akeno, believing them both to be in her way.
  • Lady Swears-a-Lot: When she's teaching English, she's teaching English swears. It's more than likely why her only animated appearance is based on her introductory chapter from the manga in the OVA which has none of this.
  • Murder the Hypotenuse: She tries to get rid of all perceived suitors of Sun's so she can have Sun to herself.
  • Peek-a-Bangs: Her hair always covers her left eye for the sneaky factor.
  • Prehensile Hair: Uses her hair as Combat Tentacles.
  • Psycho Lesbian: She wants Sun all to herself and is more than willing to get rid of anyone that gets in her way.
  • Sadist Teacher: She's pretty harsh to students early one but as the series progresses she becomes a Stern Teacher.
  • Yandere: Wants anyone attracted to Sun out of the picture so she can have Sun to herself.
  • You Gotta Have Blue Hair: Green and it's Justified in that it's seaweed.


Maruko Okhotsk

  • Adapted Out: Didn't appear in either the anime or OVAs. Lampshaded in a preview at the end of Chapter 54.
  • Anti-Magic: Can cancel out another mermaid's voice with her Reverse Sound Waves technique.
  • Because You Were Nice to Me: The reason she likes Sun so much is because Sun protected her from bullies.
  • Childhood Friends: Spent six years living in Setochi.
  • Compelling Voice: Can hypnotize other people into doing her bidding.
  • Crystal Dragon Jesus: Is 14 years old, decked out like a nun, and lives in a cathedral, but actually practices the fictional Mipopo religion.
  • Fantastic Racism: Was bullied as a child for being Ainu, making it less fantastic as many Ainu people are discriminated against in Japan.
  • Forgotten Childhood Friend: Despite talking to her the same day she saved Nagasumi, Sun completely forgot about her after moving to Saitama.
  • Hopeless Suitor: Becomes a member of Nagasumi's Unwanted Harem, and Nagasumi is (basically) already Happily Married to Sun.
  • Ill Girl: Prone to vomiting blood when stressed out.
  • Mafia Princess: Is the daughter and heir of the leader of the Okhotsk Outfit.
  • Rescue Romance: Falls for Nagasumi after he saves her life at Christmas time, although she still insists that she's pursuing him romantically for Sun's own good.
  • Unknown Rival: To Saturn, Sun's other Childhood Friend.
  • Yandere: Like Saturn, Maruko is willing to go to extreme lengths to break up Sun and Nagasumi, although in her case she at least cares for them both (being in love with Nagasumi but also being Sun's friend, and thinking Sun will benefit from losing her relationship with Nagasumi.)


Amano Edomae

  • Action Mom: Even Lunar's dad, an expy of the Terminator, is intimidated by her.
  • Adapted Out: Didn't appear in the anime or OVAs.
  • Bitch in Sheep's Clothing: She's where Lunar gets her hidden haughty attitude from.
  • Blood Knight: She taught Lunar the Song of War as a lullaby, and considered fighting off her berserk daughter playing!
  • Bring It: Her response to being sentenced to 10 years in prison.
  • Car Fu: Ran over her husband at over 100 km/h.
  • Disproportionate Retribution: She divorced and tried to kill her husband for trying to go legitimate in business and becoming Married to the Job.
  • Divorce Requires Death: Tried to kill her husband as a proxy for divorce.
  • Just Got Out of Jail: Chapter 66 begins with her release from Hokkaido Takimura Penitentiary.
  • The Maiden Name Debate: After divorcing Lunar's father she started going by her maiden name, Sagami.
  • Missing Mom: Was arrested for trying to run over her husband and given 10 years in jail for attempted murder, manslaughter, speeding, not being repentant, and contempt of court.

1/8th Figurine

  • Adapted Out: Didn't appear in the anime or OVAs.
  • Defector from Decadence: Is a noble who left the imperial court to warn Nagasumi of Minamoto no Yoshiuo's plans.
  • Harbinger of Impending Doom: Shows up and informs Nagasumi that the merpeople nobility has sent assassins to kill him following the disappearance of Akeno's overseer.
  • Invisible to Normals: Nagasumi and Akeno are the only ones she lets see her.
  • Mr. Exposition: Reveals to Nagasumi that Akeno is trying to break him and Sun up and that she has orders to kill him should breaking them up not work. She also reveals to Akeno that the top secret true objective of the Merpeople Examination - to break up Nagasumi and Sun - was set up by Minamoto no Yoshiuo so he could get Sun for himself.
  • The Nicknamer: Kept forgetting Nagasumi's name and decided to call him "Miguel" instead of "Michishio".
  • Noble Fugitive: Learned of Minamoto no Yoshiuo's plot to get rid of Nagasumi and fled to save herself from assassination.
  • Only Known by Their Nickname: Is only referred to as "Fairy-san" by Nagasumi and "1/8 Figurine" by her enemies.
  • Our Fairies Are Different: She likes being called "Fairy-san", though all that's really known about her is that she's different from Maki and Fuki despite being the same size as them.
  • Walking Spoiler: Is a key player in the manga's final arc.

Maki Yuri

  • Adapted Out: Didn't appear in the anime or OVAs, but more-or-less less fills Akeno's shoes from the anime's finale.
  • Curb-Stomp Battle: Easily defeats Jupiter and Akeno by herself. In their final battle, Akeno uses the remnants of her own sacred sword and defeats her in seconds
  • Cute and Psycho: Is unrelenting, intense, and vicious when attacking, but otherwise apologetic and a major crybaby.
  • Defeating the Undefeatable: Slices Akeno's sacred sword to pieces and dislocates Jupiter's hip with one hand when they try to stop her from killing Nagasumi. Akeno pays her back during the final battle, cleanly defeating her in seconds.
  • Heel–Face Turn: Akeno defeats her then points out that she should put her faith in 1/8 Figurine, who is an actual god, rather than Yoshiuo because someone trying to kill god is probably not the best kind of person.
  • Hired Guns: Is a black ops assassin sent to silence 1/8th Figurine and break up Sun and Nagasumi, or else kill him.
  • Knife Nut: Wields a pair of hidden blades made of the same material as Akeno's sword, and is even more skilled than Akeno.
  • Name's the Same: Has the same first name as Maki, lampshaded in a gag panel.invoked
  • Nice Girl: Pleads for Nagasumi to break up with Sun in order to save their lives. It's revealed that she truly doesn't want to fight, but does it because Minamoto no Yoshiuo promised to protect her hometown.
  • Reluctant Warrior: She doesn't want to kill anyone, so she strongly advises Nagasumi to break up with Sun but when it comes to combat she shows no mercy.
  • Sempai/Kohai: Is Akeno's kohai and former apprentice.
  • Surpassed the Teacher: Akeno taught her how to fight, and Maki is the only person she has never been able to defeat.

The Kitten

A little white kitten whom Nagasumi adopts, and a constant source of fear for most of the Seto Gang.

  • Cute Kitten: A darling little creature, which is why it is so funny to see merfolk flee in terror of it.
  • Cuteness Proximity: Every human at Nagasumi's school is instantly smitten with it upon seeing it, and even some of the merfolk like the super-cool Masa.
  • The Dreaded: To most merpeople, since they're technically fish and cats eat fish.
  • Killer Rabbit: Averted; as a little kitten, it's completely harmless. Though most merpeople who encounter it react as if the trope was played straight.
    Lunar: Well, just what do you expect?! We're mermaids, after all!
    Sun: That kitty's our natural enemy! To it, we're food!

Alternative Title(s): Seto No Hanayome


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