Played in the Dorama by Yuki Izawa
- Babies Make Everything Better: Kazuya finally starts to get over Sumire after Midori is born.
- Big Brother Worship: Until that thing with Sumire and the being a School Nurse.
- Butt-Monkey: He's somewhere between this and Chew Toy. Some of his situations (such as being prone to ulcers and happening to fall for the woman who fell for his brother) are just plain bad luck. That said, Mitsuru and Shinobu enjoy picking on him (for example, they deliberately made him roommates with Shun and ran a betting pool as to how long it would be before an Unsettling Gender Reveal happened), and his brother regularly teases him as well. People who do this to him almost inevitably feel he needs some Tough Love to grow up (except Sumire, who is completely unaware as to how Kazuya feels).
- The Dog Bites Back: Kazuya will occasionally get pushed too far. The first example was the result of learning of the aforementioned betting pool - he decks Mitsuru right in the face and storms off even after the latter says they'll use the winnings to throw him a party. Mitsuru even admits he had it coming.
- The Dulcinea Effect: This happens around most women. He chases a photographer off for Mieko, and really goes out of his way for Miya.
- Earn Your Happy Ending: Kazuya eventually matures, gets everyone's respect, falls in love, and even begins to earn his girlfriend's respect, but the road is not easy (not least of all because it amuses Shinobu too much to let it be easy).
- Embarrassing Nickname: Suka-chan, but he gets used it.
- Fragile Speedster: Kazuya can run 100m in 11 secs, despite not being particularly robust physically.
- Nosebleed: Though in his case, nosebleeds are usually the result of stress instead of arousal. Of course, given his love history, arousal = stress.
- Not So Above It All: Especially when it comes to bringing Mitsuru and Shinobu down a peg.
- Tiger Versus Dragon: Played for Laughs when Shinobu convinces Kazuya that he and Midori are rivals for Sumire's affections, and Kazuya imagines an Animal Battle Aura of this type around them, with Midori as the tiger and Kazuya as the dragon.
- Weak, but Skilled: He can outrun anybody, despite said lack of actual physical strength.
Played in the Dorama by Hiroki Suzuki
- Attractive Bent-Gender: The desire many of the dorm residents have for Shun to really be a girl is something of a Running Gag.
- Dude Looks Like a Lady: Shun is regularly mistaken for a woman - soft features, beautiful long hair, short and slender build, and even a feminine voice (emphasized by always being voiced by women in animated adaptations). In fact, the first indignity that Mitsuru and Shinobu inflict on Kazuya is convincing the latter that Shun is a woman, and then running a pool with the rest of Greenwood to see how long it would be until Kazuya finds out.
- Family Business: His family owns a chain of hotels and ryokan.
- Have I Mentioned I Am Heterosexual Today?: Does this a couple of times, but it's justified given the assumptions people tend to make about him based on how he looks and acts.
- Inadequate Inheritor: Until his sister was born. Also seems to the root of his Freudian Excuse for being unusual.
- Keet: He's not as hyperactive as most, but he's perky and cheerful and most everything else a Keet is.
- Nosebleed: The one character to get one due to the standard reason - due to being mistaken for a woman at a pool, he was pushed into the women's changing room.
- Unsettling Gender Reveal: While he first appears as a girl, it eventually turns out that he's a man all along.
Played in the Dorama by Riki Miura
- Chick Magnet: If there's a woman on-panel, there's an even chance that she's going to be taken with him. Even lesbians want him. Not surprisingly, when Valentine's Day rolls around, he by far receives the most chocolate of anyone in the cast. He doesn't even have to try (though it's implied that he's particularly successful when he does).
- Family Business: His family owns and cares for a Buddhist Temple.
- Happily Adopted: Subverted in a way, since even though he clearly loves his family and they love him, he considers himself an outsider and doesn't think he should inherit the temple.
- Healing Factor: His face can heal from even deep cuts and black eyes in seconds.
- Inadequate Inheritor: He's technically the oldest, so he's first in line to inherit his family's temple, but because he's adopted, there is resistance to this outside of his immediate family. He seems to agree that he shouldn't inherit.
- Karma Houdini: Played for laughs in one Day in the Limelight. Once, he and Shinobu realized that they were low on funds and said so out loud - right as Kazuya, who had spent nearly two years being their Butt-Monkey by this point, overhears them, so Kazuya immediately notifies the rest of Greenwood to hide their funds so that they can't be brow-beaten or tricked into covering for the two. Mitsuru and Shinobu have a day out and, due to a combination of Contrived Coincidence, Mitsuru's kind nature, and Shinobu's skill at gambling, the two manage to have a comfortable and profitable day despite Kazuya's attempts at making them miserable.
- The Only Way They Will Learn: In particular, when he leaves Kazuya in charge of the dorm for one night, though Shinobu undermines it somewhat by telling Kazuya almost immediately after Mitsuru leaves.
- Pre Ass Kicking One Liner: Mitsuru opens the library fight with one of these."I thought all night, and this is the best I could think of."
- Red Oni to Shinobu's Blue
- Shirtless Scene: Furo Scenes not withstanding, this happens a couple of times, when Nagisa forces him to strip after she kidnaps him, and lampshaded when he makes the mistake of standing near an open window without a shirt on during one of the stories set during the summer and his fangirls get photos.
- Urban Legend Love Life: For all that he's a legendary Chick Magnet, he's never shown actively pursuing anyone. He's also easily flustered by panties for someone who's supposed to have a lot of experience.
Played in the Dorama by Yuuichi Sato
- Big, Screwed-Up Family: His parents are strict and emotionally distant, enforcing a competition between their three children. His elder brother eventually snaps and more or less tries to abandon the family and pursue a low-stress life as a photographer. His sister is regularly mistreated for being female, until she snaps and acts out as a low-level villain. And Shinobu is a manipulative sneak, and it's shown in flashback that he pretty much completely lacked scruples until meeting Mitsuru.
- Blue Blood: The youngest son of a politician, which is about as close as modern Japan gets to nobles, not counting the emperor's family.
- Hidden Heart of Gold: Subverted, in that while he certainly isn't the outright Jerkass he frequently comes off as, he's still not a particularly nice person underneath the facade.
- High-School Hustler: Of the "running betting pools" variety. In particular, he's the one actually responsible in the opening story for maintaining the pool as to how long it would be until Kazuya learns that Shun is a man. Also, in the Day in the Limelight, at one point, he uses his gambling skills at a pachinko parlor to increase what meager funds Mitsuru is able to scrounge up. He isn't tremendously successful, but he does pull a profit.
- Karma Houdini: Subverted once when Mitsuru was able to lure him to a public fight in the library to damage his publicity, which resulted in a double subversion when Shinobu admitted that he was glad it happened because he realized it was possible for the good guys to be happy.
- Played for laughs in one Day in the Limelight. Once, he and Mitsuru realized that they were low on funds and said so out loud - right as Kazuya, who had spent nearly two years being their Butt-Monkey by this point, overhears them, so Kazuya immediately notifies the rest of Greenwood to hide their funds so that they can't be brow-beaten or tricked into covering for the two. Mitsuru and Shinobu have a day out and, due to a combination of Contrived Coincidence, Mitsuru's kind nature, and Shinobu's skill at gambling, the two manage to have a comfortable and profitable day despite Kazuya's attempts at making them miserable.
- Motive Rant: Shinobu gives one of these to Mitsuru when he admits he's "picking up votes" for Saiki.
Played in the Dorama by Kengo Ohkuchi
- Big Brother Instinct: He's extremely protective of Kazuya, although he knows it's somewhat unhealthy. He consequently tries to be hands-off with Mitsuru and Shinobu's treatments of Kazuya (but he's not exactly subtle if he thinks things may go too far).
- The Beard: Sumire's cousin accuses Kazuhiro of marrying her to cover up the fact he is gay. He was wrong.
Played in the Dorama by Shion Nakamaru
- Big, Screwed-Up Family: Given her parents' almost Machiavellian stance towards child rearing and Shinobu's downright devious behavior, it's little surprise that she ends up a bit off-kilter herself. That said, given that she thought the eldest brother, Akira, was also an aloof asshole when he was just barely holding it together without having a breakdown (and, given that he ran away from the family and surrendered any claims on inheritance, even that eventually slipped), it's clear that some of her issues are just her own insecurities magnified by how she's been treated.
- I Will Punish Your Friend for Your Failure: Nagisa tries to get Shinobu to bend to her will by kidnapping Mitsuru and threatening to hurt him. It doesn't work.
- The Resenter: In part due to being automatically disqualified for advancement in the family due to her gender, she ends up having a grudge against both of her brothers.
- The Un-Favourite: As noted, she's basically passed over for everything in the family due to her parents' sexism. That said, her other attitude issues aren't helping her cause any.
- Big Brother Worship: He positively adores Shun, and in fact he runs away from home in part to protest that his mother had a daughter, thereby preventing Shun from inheriting the family inn (the Kisaragis noted in-story as practicing matrilineal inheritance with regards to the inn).
Played in the Dorama by Aoi Yoshikura
Played in the Dorama by Yukari Fukui
- The Ditz: See Oblivious to Love below. She basically ignores every single sign that Kazuya fell for her hard and fast. She also tends to think that his anger and resentment is because she worries that Kazuya thinks she stole Kazuhiro from him (when Kazuhiro knows it's because Kazuya feels that Sumire was the one stolen from him).
- Oblivious to Love: Because she only has eyes for Kazuhiro, Sumire is completely oblivious to the fact that Kazuya falls hard for her. She sees him as they younger brother she never had, and she's consequently hurt that he decides to live in Greenwood rather than commute from their home.
- Arranged Marriage: To Akira, until he got himself disinherited.
Played in the Dorama by Hiroshi Nagao
Played in the Dorama by Enoku Shimegi
- All Take and No Give: Type B. And not only is Tenma himself guilty of it, but their parents also reinforce it by constantly telling Miya that Tenma is wonderful and does so much for her.
- Catchphrase: "That's right!"
- Childhood Marriage Promise: According to him, anyways. Sumire being who she is probably didn't realize he was being serious.
- Forgotten Childhood Friend: Cousin, to be precise. Infiltrates Ryokuto in an attempt to prove that Kazuhiro married Sumire under false pretenses.
- Gratuitous English: Justified since he's been studying in America.