The male protagonist. He used to live with his grandfather before moving from the country to the city for his first year of high school.
- Above the Influence: In the manga, it is averted. Kouta admits that he likes Chizuru and is not above doing perverted things with her in private, although he does need some coaxing.
- Accidental Misnaming: Kouta gains the name "Great Erotic King" due to his classmates misunderstanding the situation he ends up in. Amusingly in the manga, when Nozomu leaves his classmates apologizing for calling him that, since she left citing that Kouta would only ever really love Chizuru. The next page, when Nozomu comes back, saying she's going to be his mistress in a Threesome with him and Chizuru, they give up and go back to calling him that again. Apparently this is a form of foreshadowing, as recent developments in the manga from Saku hint that Kouta was some form of king.
- Accidental Pervert: Pretty much how he got the nickname "Great Erotic King".
- Babies Ever After: Has a daughter with Chizuru.
- Black Comedy Rape: Many, many times (basically the plot of the anime), although Kouta isn't entirely unwilling, and it's usually not played up as seriously as it could be. Chizuru's constant, aggressive attention labels Kouta as a huge pervert at school: at one point, Chizuru decides to have sex with him in the middle of the street and takes off her clothes, only to have her barrier shattered. She goes furthest on the last episode: tired of waiting for a confession, she abducts and sets out to rape him in an empty classroom, while the helpless, almost-crying Kouta covers his face and begs her to stop (which she does at the last minute, when his rejection finally hits home). She means well; she just doesn't know the meaning of restraint.
- Disproportionate Retribution: It seems that Kouta gets blamed and subsequent flak for alleged molestation even though Chizuru and Nozomu are the ones who initiate it, and usually prevent him from being able to escape by mounting on top of him, or pinning him down with a hug.
- Double Standard: Abuse, Female on Male: Kouta gets nailed with a trash can. To be fair, Chizuru meant to throw it at Nozomu who was clinging to him at the time, but she managed to dodge it.
- Double Standard: Rape, Female on Male: Whenever Chizuru and Kouta are caught in a compromising position, which happens at least Once per Episode, Kouta is the one who gets blamed even though Chizuru is the one who started it and Kouta was constantly saying "No" and "Stop".
- Flash Step: Kouta can move with inhuman speed when necessary to dodge Chizuru's more overt advances. The way she'll attempt a Marshmallow Hell attack on him, only to grab thin air as he instantly appears behind her, is strangely reminiscent of a Dragon Ball Z-style combat...
- Fusion Dance: If a yokai and human are willing, they can temporarily fuse... mostly for fireball-throwing. Strangely enough, this is insinuated to require a deep emotional bond between the two, whereas Kouta and Chizuru can do it almost immediately upon meeting each other.
- Lovable Sex Maniac: In chapter 41, after trying to deprive himself of ecchi behavior to study for a test, saw a girl grab Chizuru's breasts and... well... And because he did not get enough sexy time, he started generating a mighty aura that knocked out all the males around the school and managed to make every girl in the school want his body.
- Love Triangle: In the middle of one with Chizuru and Nozomu.
- Marry Them All: The manga starting in the middle of volume 3. Although Kouta at first asks Chizuru to become his wife, Nozomu later becomes Kouta's mistress, what's more Chizuru no longer seems to be bothered and Kouta seems to be all for a threesome.
- Marshmallow Hell: Within the first five minutes, no less! Chizuru even lampshades this by demanding Kouta beg to be spoiled when she does it after a certain point. As the series goes on it actually becomes Marshmallow Heaven for Kouta, and she uses it to relieve him from his stress. To the point that in chapter 41, one week after he decided not to do anything sexual with Chizuru until the exams, he jumps with a mad expression and bloodshot eyes when he's teased a bit too much with Chizuru's breasts. Yes, he's literally addicted to them!
- Nose Bleed: Kouta suffers from this a lot, thanks to Chizuru and Nozomu constantly fighting over him, usually while stripped down.
- Not So Above It All: Kouta starts out completely unwilling to join in with Chizuru's (and Nozomu's) antics, but has faltered a few times once, when she conned him into spanking her, and enough times with her Marshmallow Hell routine that she and him now have a pet word for it, asking to be "spoiled". Kouta is reluctant to initiate things and doesn't want it done in public, but otherwise he is surprisingly willing for a character of his type. At least twice he is mentally telling himself he is about to have sex with Chizuru only for the pair to be interrupted. At one point in the manga, Kouta says specifically that he doesn't want to go all the way only because he wants to wait until they are married and wants to graduate before that happens so he can be a worthy husband for Chiruzu.
- Ordinary High-School Student: Weird nickname and weirder girlfriends notwithstanding. Although several of the other students are quick to point out there has to be something special about him to be able to merge with Chizuru so readily, to say nothing about the absurdly powerful foxfires they can create together. Later, Saku goes further, flat out calling him the "Key" (compared to Chizuru's "Door") and calling him a king.
- Orochi: He is the reincarnation of Susanoo.
- Parental Abandonment: Kouta moved from the country to the big city to go to school and lives alone. This ends up being more than it appears in the manga. In chapter 20, on page 34, Saku the wolf yôkai notes that a clue to the mystery surround Kouta is how he seems to only have a single true relative.
- Sleep Cute: Does this with Chizuru and Nozomu in chapter 34. It's a very sweet moment between the three of them, especially when you see that both Chizuru and Kouta are holding Nozomu close. Then Akane decides to interrupt.
- Tiny Guy, Huge Girl: Well, considering Chizuru is Really Four Hundred Years Old it's not too surprising that she's more than fully grown up compared to the teenage-looking Kouta.
- Unwanted Harem: Chizuru and Nozomu are both quite forward, while Kouta has Heroic BSODs every time they come near him doubly so if they're half-naked, which is about 50% of the time. Kouta makes absolutely no attempt to attract the two, since they both go after him on their own for unexplained reasons (although Chizuru mentions he "smells like the forest" at one point). Taken Up To Twelve in chapter 41.
- Will They or Won't They?: They finally consummate their relationship in chapter 47.
Chizuru is second-year female student at Kouta's school. On the outside she appears to be a well endowed teenage girl, but she is in fact a powerful kitsune.
- Babies Ever After: Has a daughter with Kouta.
- Barbie Doll Anatomy: Very noticeable during her Shower Scene. Also noticeable in the manga, which would be very, very explicit if not for this trope.
- Body Sushi: Chizuru gets into a body-sized sushi boat naked in attempt to hit on Kouta.
- Boobs of Steel: Chizuru's a very powerful yôkai, as well as a very busty one. These attributes are definitely related. The plotline of episodes 9 and 10 is the sealing of her power and her attempts to regain them. More importantly, Chizuru barely notices her powers being gone the entire time it's the sudden lack of cleavage she's utterly freaked out by.
- Brought Down to Normal: When Chizuru loses her Boobs of Steel.
- Chocolate of Romance: In an OVA DVD, Chizuru is trying to figure out what kind of chocolate to get for Kouta for Valentines day, her various ideas being a chocolate bar wedged inbetween her breasts, chocolate molds of her breasts, and finally, a chocolate bikini, which Kouta is to eat off of her. She just ends up giving him a traditional box of chocolates.
- Clingy Jealous Girl: And it seems Nozomu enjoys provoking her into this trope.
- Emergency Transformation: In a pinch, Kouta and Chizuru can merge, turning Kouta into a male kitsune with absurd power, temporarily. Fortunately, it's not permanent. Although Kouta is gaining kitsune powers while human, which leads Chizuru to think that their merging will eventually turn him into a yôkai. It turns out that the "kitsune" powers Kouta manifests are actually those of the Yamata no Orochi, which is why his tails tend to appear as serpentine heads.
- First-Name Basis: Kouta starts calling Chizuru by her first name (on her demand) within the first chapter. But she is a bit pissed that he uses such a formal honorific as -san, which reminds her she's quite a bit older than he is.
- Fusion Dance: If a yôkai and human are willing, they can temporarily fuse...mostly for fireball-throwing. Strangely enough, this is insinuated to require a deep emotional bond between the two, whereas Kouta and Chizuru can do it almost immediately upon meeting each other.
- Gainaxing: If she wasn't supernatural, she'd have back problems.
- Hypocritical Heartwarming: When Nozomu shows up, she often complains that she is a pervert who wants to take advantage of Kouta.
- Horny Devils: Horny doesn't begin to describe Chizuru. And judging by her reputation, her mother seems even worse, which is saying a lot.
- Kinky Spanking: An episode end with erotic spanking happening between Kouta and Chizuru. Kouta was the one delivering the spanking and Chizuru is the one who tricked him into doing it.
- Lethal Chef: She hilariously captures some students, ties them up, and forces them to taste test some food for her. Interestingly, while the three female students pass out, apparently the two ninja girls enjoy the food.
- Love at First Sight: Claims this about Kouta. Saku, and other events, suggest something less simple and idealistic is behind their swift connection. In the manga it is also suggested that Kouta's hidden power or something else super natural may have something to do with this.
- Love Triangle: With Nozomu and Kouta.
- Lovable Sex Maniac: A rare female example. Her lust is supported by Japanese mythology though, where fox yôkai were noted for, among other things, their beauty and desire to seduce humans. Chizuru of course reserves all of her sex mania for Kouta. Being a centuries old virgin probably adds to her sexual frustrations.
- Megaton Punch: Does this to Tayura a lot.
- Ms. Fanservice: Has the biggest bust of any girl in the cast and is quite unashamed of it, too.
- Naked People Are Funny: Scene getting boring? No worries, because Chizuru will probably strip soon, just in time for Kouta to get blamed for it. Unless he doesn't, in which case Nozomu will show up, already naked, right afterwards.
- Naughty Nurse Outfit: Lampshaded in chapter 12 of the manga, when Chizuru wears a nurse outfit out of nowhere.
- Never My Fault: When she ends up accidentally hurting Kouta, she will usually blame it on someone else, especially Nozomu.
- Nice Girl: In spite of being unabashed about her appearance, she's very friendly once you get to know her.
- Orochi: Chizuru is revealed to be the reincarnation of both Kushinada and the Yamata no Orochi who's power surfaces when Kouta is in danger.
- Paper-Thin Disguise: When Chizuru wants to pass for her brother to be in the same class as Kouta, she just dresses like him and puts a leaf on her head, which is the a common depiction of a youkai's ability to another's shape.
- Parental Substitute: For Ai and Ren.
- Please Put Some Clothes On: Chizuru's constantly removing her clothing in attempts to get Kouta in bed, Nozomu follows suit if she's around. Chizuru, when she possesses Kouta, turns into a spirit, leaving her clothing behind in a pile; when she exits, she's nude.
- The Power of Love: Chizuru can only hop into Kôta's body because of their deep love for each other, fostered over the 10 whole minutes they knew each other before they did it the first time. Subverted, in that apparently it is Kôta and/or Chizuru's hidden legacy as the Key and Door, not love, that makes them so spiritually compatible.
- Pretty Free Loader: While Chizuru does not live with Kouta, she does not help her brother with anything around the house.
- Really 700 Years Old: She is really 400 years old but looks like she's 16-18.
- Shaking the Rump: In Episode 6, while dressed in a pink kimono, Chizuru very provocatively does this to tease Kouta.
- Shout-Out: In chapter 30, when Chizuru asked Ai and Ren why they didn't tell Akane the truth when she saw them holding on to Kouta's tails when he was fused with Chizuru, they tell her that they thought of them as a hero of justice from fusion while doing the Fusion Dance pose from Dragon Ball Z.
- Sleep Cute: Does this with Kouta and Nozomu in chapter 34.
- Suicide as Comedy: Chizuru tried to hang herself in Episode 9 when her breasts are magically shrunken and she suffers from A-Cup Angst, and was just about to be talked out of it by Kouta's kind reassurance until Nozomu grabs her chests and cheekily quips "I win!", prompting her to leap to the noose with renewed gusto.
- Tiny Guy, Huge Girl: Considering Chizuru is Really Four Hundred Years Old it's not too surprising that she's more than fully grown up compared to the teenage-looking Kouta.
- Too Kinky to Torture: In chapter 36, Chizuru's punished for cheating in a game by being tied up, dangling from the ceiling, and blindfolded. She remarks that she thinks she could get used to this.
- Top Wife: The end of the series establishes Chizuru as the Official Couple and girl that will marry Kouta. The Stinger, however, has Nozomu return and state that she will settle for being The Mistress and Chizuru agrees to it.
- Virgin Power: In the manga, during their fight with her ex, Saku, Chizuru reveals that the muffler she gave Kôta has a protective power because of the virgin hair she used in its construction. Saku just stares at her in disbelief.
- Weirdness Censor: Chizuru uses a magic barrier in the middle of the street to ensure no one will interrupt her as she attempts to hold Kouta down and have her way with him. Kouta kisses Chizuru with the purpose of intentionally fusing with her. This upsets and saddens Chizuru who at that moment was overjoyed that Kouta had taken the initiative to kiss her, but it provides Kouta an opportunity to explain to her about why he is hesitant about simply randomly having sex.
- Will They or Won't They?: They finally consumate their relationship in chapter 47.
Nozomu is a first year female student at Kouta's school, and a wolf-spirit.
- Barely-There Swimwear: In the Beach Episode, Nozomu tries to pass off three bandages (two little ones and a big one) as a swimsuit. Oblivious as to why the other girls object to it, she (or rather Chizuru) is eventually forced to purchase a more normal swimsuit at said beach.
- Big Eater: Don't let Nozomu's petite figure fool you. She has quite the ability to wolf down large quantities of food. The first time we see her, she's gorging on meat, and in one of the OVA's, she eats a whole watermelon by herself.
- Clingy Jealous Girl: Is plenty clingy to Kouta, sometimes just to get Chizuru to get clingy too.
- Emotionless Girl: Although she does seem quite capable of love and lust. In the manga, which shows her alone at times, it reveals that she isn't emotionless but only when she's in her yôkai form. Or when she's alone. Or maybe her emotions cause her yôkai form to pop out.
- First-Name Basis: She calls everyone by their first name (without even honorifics) right off the bat, even if she just met them.
- Late for School: Subverted with Nozomu acting out this and the New Transfer Student trope, even though she technically joined in the previous episode. Doubly subverted as she continues speaking in her monotone voice and ignores what Kouta is saying, in lieu of responding with her half of the trope regardlessly, all while kidnapping Kouta from Chizuru.
- Lethal Chef: Nozomu doesn't seem to be much of a cook, as Kouta passes out after eating hers and Chizuru's.
- Love Triangle: With Kouta and Chizuru.
- Not So Above It All: In the manga, this is Nozomu's defining character trait... Sort of. She constantly, constantly berates and complains about how Chizuru (and, to a lesser extent, Kouta) acts... but all the while she's complaining, she's also joining in and showing that she's at least as, if not even more, perverted as Chizuru. For example, in Chapter 28, she accuses Chizuru and Kouta of smelling like two animals in heat (as a Wolf youkai, she has an enhanced sense of smell) when she interrupts them during a heavy petting session in the bathtub... only to strip naked and go even farther than Chizuru was going (rather openly getting Kôta to perform oral sex on her, when Chizuru was only rubbing up against him).
- Please Put Some Clothes On: If Chizuru's naked, this reaction will be soon follow.
- Really 700 Years Old: Is of indeterminable age but looks 13-15.
- Shout-Out: Episode 3 references Neon Genesis Evangelion when Nozomu collides with Kouta in the same manner in which Rei and Shinji collide in the final episode of Eva. The shout-out continues when Kouta falls on top of Nozomu in a pose reminiscent of when Shinji fell on top of Rei in Episode 5. This is made all the more funny by the fact that the whole incident was set up by Nozomu.
- Sleep Cute: With Kouta and Chizuru in chapter 34.
- Sleeps in the Nude: Nozomu lives by herself in an expensive but empty penthouse apartment where she always sleeps naked on the floor.
The younger brother of Chizuru and Kouta's classmate.
- Butt-Monkey: The eternal errand boy and subject for slapstick humor.
- Disproportionate Retribution: Occasionally happens to him.
- Double Standard: Abuse, Female on Male: He's on the recieving end of a lot of Chizuru's attacks.
- Megaton Punch: Is on the recieving end of a lot of these. Usually from Chizuru.
- Shout-Out: In chapter 32, Tayura "explains" to Akane that Kouta and Chizuru were doing Cosplay, and Ai and Ren were also cosplaying. The visual for the twins' supposed cosplay is clearly The Familiar of Zero.
The class representative of Kouta's class.
- Alliterative Name: Akane Asahina
- Cannot Spit It Out: In the manga, Akane returns Tayura's feelings but is too shy to say anything. (This is dropped from the anime for time.)
- Class Representative: Despite her best efforts, she doesn't enforce the school rules as well as she'd like to. One can thank this on her being unable to hold her liquor.
Ren Nanao & Ai Nanao
Ren and Ai are twin first-year sisters at Kouta's school. They're spirit hunters who live in a very poor temple.
- Defeat Means Friendship: After the ninja twin's various attempts to get rid of Chizuru fail, they get invited to dinner with the main cast. Also subverted in that the main cast has no idea they're responsible for the current trouble.
- Fundoshi: When in their Ninja garb.
- Magic Skirt: Averted, most notably in a particular scene with the two.
- Meaningful Name: "Ai" and "Ren" are both words that mean "love".
Mio is a second year student with a shy nature who hangs around with Omi.
- Does This Remind You of Anything?: She's a frog spirit that has oils that are basically a cure-all. Several times Chizuru and others need her to give up some. How do they do so? Get her to dress in a School Swimsuit and squat in an old metal tub until they... get their oil. This is actually a reference to a Japanese old-wives' tale (Akira Kurosawa mentions it in his autobiography). There was indeed a frog whose secretions were used as medicine, and the best way anyone had found to get the stuff was to put the frog in a box with mirrors on all sides; as the theory went, the embarrassment and horror of seeing its own reflection would cause it to perspire profusely.
Yukihana is a yuki-onna and a ninja who works under Tamamo at the Tama no Yu hot springs resort, and at her beachside restaurant Tama no Ya.
Kouta's younger sister.
- Alliterative Name: Minori Mitama
- Artificial Human: She is revealed to be a partially successful attempt to create a vessel for Susanoo. Kouta was the successful vessel.
- Big Bad: She called Kouta "onii-chan" and can perform a Fusion Dance with her servant to transform into a male bat-winged demon, appears to be this, although she is only a pawn for the Eight Houses of Kazunoha's leader, Shiki Mitama.
- Gender Bender: Minori changes from a young girl to a teenage boy when fused with Nue.