Buffy Speak: "All we have to do is kill this final boss thingie, right?"
Bunny-Ears Lawyer: Hiyoko may be one, since she's apparently already passed a year at one of the most demanding private high schools in the world, despite being a cave-dwelling barbarian. She also sometimes protests things in rather erudite terminology for someone who couldn't finish her reading assignment.
Carnivore Confusion: Hiyoko's barbarian love for eating meat is a major plot point in certain storylines.
Contemporary Cavewoman: Complete with actually living in a cave! Although, she still somehow has a cell phone and other things.
Dumb Muscle: Hiyoko starts with 1 wisdom, 800 vitality, and 5 charisma, and she does not get more than about 35 to 40 possible points of stat increase throughout the game.
Genius Bruiser: If Hiyoko attends math class on all the elective days, she can become the best in the class.
Evil Vegetarian: An interesting inversion to this trope. She is a barbarian woman who hunts for her own meat, red being her favorite. But based on her ability to see the ghostly Nageki, she has a pure heart.
Fantastic Romance: Even disregarding the whole pigeon-dating thing, Hiyoko's relationship with Fujishiro Nageki ends with the revelation that he committed suicide five years ago, and his time as a ghost has come to an end.
Featureless Protagonist: Hiyoko has a strong, vivid personality, but there is no canon appearance for her, nor does she have a voice actress. In the manga her speech balloons feature cartoon pictures of meat to indicate that she's the speaker, and in the (ridiculous] mushroom chapter she's shown completely concealed by mushrooms and apparently is quite physically expressive!
She is equally featureless in Anghel's world, where she was sealed inside an opaque cage of ice as a punishment for disobeying God.
Huge Schoolgirl: Human, to a cast full of birds. When drawn with the gijinkas or human forms of the rest of the cast, fans universally make her much shorter and smaller than everybirdie except maybe Nageki, which doesn't line up at all with how she's treated in game.
I Ate What?: Courting Dr. Shuu? He sends Hiyoko a lovely roast bird for Christmas... after finding Yuuya going through his desk for the last time. Ho ho ho ho...
Killed Off for Real: At the beginning of the Bad Boys Love route. And in the middle of the same route.
The Lancer: To Nageki in the last two chapters of Holiday Star.
Large Ham: "But we can’t just let him break the rules like that, sir! The system will collapse and well all turn into kulaks and dissenters!"
Love Martyr: Hiyoko can be this if she pursues Shuu. It doesn't end well.
Masculine Girl, Feminine Boy: Hiyoko and Ryouta. Ryouta, the boy, is a gentle, very caring "vegetarian male" who loves cooking and frequently crossdresses in fetishistic maid or magical girl costumes for his various jobs. Hiyoko, the girl, is a tough, impulsive cavewoman who can't concentrate without red meat in her belly (mostly from animals she kills either bare handed or by smashing with weapons).
Magical Girl Warrior: She becomes one of these in Holiday Star's Absolute Zero chapter to protect the school from Tohri blowing it up with his lasers.
No Fourth Wall: Hiyoko clearly does not have a fourth wall. She introduces herself and all the love interests to the audience, needs a reminder to check the date in the upper-left corner of the screen, and interrupts the fake credits roll after Azami and Blaster hook up to point out that her story isn't over yet, so the game can't be either. In the manga, she points out that she never appears directly because the story is told from her point of view, "like an FPS!" In the sequel Holiday Star, she and Ryouta discuss visual novel mechanics when Sakuya unwittingly triggers an event, and at the beginning of the fourth episode she recaps the previous events to the audience, despite Nageki's insistence that the players aren't that stupid. She even comments that she's been friends with the Grim Reaper since the demo version of the original game, apparently from all the possible bad ends she's had.
Orphan's Ordeal: Her parents were killed years ago in a failed diplomacy attempt with the birds. This explains why she lives by herself in a cave as a hunter-gatherer.
Plucky Girl: Nothing gets her down for long. Not even being unintentionally killed by her best friend/love interest and then cut up into pieces by a mad doctor keeps her from taking an active role in the plot and helping Ryouta when he needs it the most.
The Quest: For the true pudding, if she romances San Oko.
Raised by Wolves: In the sequel Holiday Star, Hiyoko claims she was adopted by a pack of jackals in the wilderness. In the "Bad Boys Love" route of the original game, however, her parents are clearly mentioned, so she presumably wasn't raised solely by the jackals.
Token Human: Hiyoko is the only human at a school for... sapient birds.
Yuuya (paraphrased): You stand out like a poppy in a field of rye.
Trademark Favorite Food: When Sakuya asks Hiyoko what she loves, she answers "udon." Though Hiyoko also can't sit still in class unless she's had some red meat, as she tells Ryouta in the first cutscene.
Too Dumb to Live: She may be this way based on any friendly interactions with the deadly Dr. Shuu. For example, hanging around his infirmary or continuing to hang around him when she encounters him at the shrine.
Unwilling Roboticisation: In the extended BBL route, the bird characters are attacked by a scarecrow robot after they are trapped in the school. Turns out that the Dr. Shuu used the murdered Hiyoko's brain to power it.
He has been friends with Hiyoko since he was a chick when she found him on the ground and returned him to his nest.
Animal Stereotypes: The common Rock Dove is just a regular guy who may get overlooked in favor of the more "interesting" birds.
Attractive Bent-Gender: According to the manga, "Coolene" is the star of the maid cafe, and Ryouta takes pride in this.
Bad Powers, Good People: The "Bad Boys Love" route indicates this of Fujishiro Nageki when he was alive; he was the carrier for a fast-acting lethal-to-humans virus, and committed suicide to stop Dr. Shuu's attempts to weaponize it. By the end of the storyline (assuming you get the good ending), Ryouta becomes a carrier for the same virus and chooses to be isolated to prevent it from spreading, hoping only that he'll be able to be cured some day.
Brainwashed and Crazy: Ryouta becomes this for Dr. Shuu during BBL. First, Shuu reveals that Ryouta had killed Hiyoko via the Charon virus he was carrying. Second, Shuu reminds Ryouta that Ryouta had expressed a wish to him after witnessing the traumatizing Hatoful House incident years ago, and that wish was for humans and birds to no longer fight one another. Finally, Shuu explains that with humanity extinct by Ryouta's Charon virus, humans and birds would then no longer war with one another. By now the already distressed Ryouta breaks down emotionally and agrees with Shuu to become a disease-ridden super soldier in which to eradicate humanity.
Break the Cutie: The ending to his route has shades of this with his mother's death and subsequent fear of getting into a Mayfly-December Romance with Hiyoko and putting her through the same ordeal. And then there's the Bad Boys Love route, which hits him with a massiveTrauma Conga Line.
The King does this when he hits the metaphor right on the money and points out how jealous he is of Nageki. Of all the birds, he's the one who comes close enough to the Despair Event Horizon that the player needs to choose the right dialogue option to prevent him from giving up and letting the King assimilate him.
Betty and Veronica: During Holiday Star's TDTNS chapters Ryouta gets increasingly anguished about the possibility of beloved childhood friend Hiyoko getting romantically involved with the library ghost-bird Nageki. Even if in reality Hiyoko and Nageki are platonic friends at best, Ryouta would view himself as the "Betty" and Nageki as the "Veronica" in this situation.
Despair Event Horizon: He crosses this in BBL once he learns that he accidentally killed Hiyoko with the Charon virus he was carrying.
In Holiday Star's fourth chapter if Yuuya chooses the wrong option in which to counsel Ryouta, then Ryouta will become even more anguished about Hiyoko possibly leaving him. Right after Ryouta bitterly retorts that Yuuya doesn't understand his predicament, Ryouta then lets himself get absorbed into The King's twisted hive mind.
Disappeared Dad: Where's his dad? The Bad Boys Love route reveals that his dad died from a disease he contracted during his research, and Ryouta remembers little about him. Supplementary material shows that Ryuuji couldn't remember just when Ryouta's birthday was.
Glowing Eyes of Doom: In BBL Ryouta gains red ones after he becomes brainwashed and crazy via Shuu. They accompany his overall red glow he gains after agreeing to becoming a disease-ridden super soldier in which to eradicate humanity.
Green-Eyed Monster: Even if Ryouta seems like a gentle and kind friend at all other times, in Holiday Star he will let himself get absorbed into The King's twisted hive mind if his jealously towards Nageki's current relationship with Hiyoko overwhelms him.
Hidden Depths: Very aware of mortality. Afraid of change, especially when that change pertains to his relationship with Hiyoko.
Ill Bird: It's mentioned that he has a weak stomach. This is because Doctor Shuu has been deliberately weakening his immune system in secret to make him an ideal carrier for a human-eradicating virus.
Informed Attribute: When Hiyoko first introduces Ryouta, she describes him as mischievous but kind. However, compared to the other wacky students at St. Pigeonation's, Ryouta seems like the only sane one alongside the quiet Nageki. Perhaps Ryouta was more mischievous with Hiyoko while they were growing up together, yet his heightened responsibilities during his teenaged years (such as caring for his ill mother by himself) has left him no more opportunities to be mischievous and playful as he was during his childhood.
Magical Bird Warrior: He becomes one of these in Holiday Star's Absolute Zero chapter to protect the school from Tohri blowing it up with his lasers.
Masculine Girl, Feminine Boy: Hiyoko and Ryouta. Ryouta, the boy, is a gentle, very caring "vegetarian male" who loves cooking and frequently crossdresses in fetishistic maid or magical girl costumes for his various jobs. Hiyoko, the girl, is a tough, impulsive cavewoman who can't concentrate without red meat in her belly (mostly from animals she kills either bare handed or by smashing with weapons).
Meido: He dresses up as this for the school festival, and one of his possible jobs is at a maid cafe. Hiyoko can join him on his route.
Ninja Maid: In the manga, he defends his career from Sakuya's classism by claiming that maids are the new ninja.
Missing Mom: His mother dies near the end of his route.
Nice Guy: He works multiple jobs to care for his ill mother and remains stoutly loyal to childhood friend Hiyoko in whatever her pursuits.
Only Sane Bird: When something bizarre happens around Hiyoko, Ryouta will usually be there to make some comment about it.
Red Eyes, Take Warning: Subverted. He's Hiyoko's childhood friend and one of the most kind-hearted characters of the cast. Additionally many Rock Doves have naturally red or orange eyes in real life.
Supreme Chef: Hiyoko often mentions how delicious Ryouta's cooking is.
Unlucky Childhood Friend: Holiday Star reveals that he's jealous of Nageki. Characteristically, he blames himself for not acting on his feelings sooner.
Wholesome Crossdresser: He has a tendency of showing up in female clothing throughout the game. You will always see Ryouta in a maid's uniform for the Maid Cafe, and if you follow him down his route you'll find he also works at a transvestite cafe... and he goes by the name "Coolene". Of course, he's working there so he can support his mother, but you can ask him to get a different job.
Gets even more clothing of the other gender in Holiday Star, such as a nun... and a Magical Girl.
The president of the student council and heir of a wealthy family, he's extremely snobbish and looks down on anyone he perceives as inferior to him, which is almost everyone else.
Abusive Parents: Sakuya's father, while not physically abusive, has incredibly racist views that he indoctrinated his son with and seems to care more about Sakuya's prospects as the future family heir than his own personal wishes, something confirmed in Sakuya's extended ending where he's kicked out of the house after he confesses to his father that he wants to become a musician. Not only that, but the Bad Boys Love route reveals that said father refused to feed his stepson Yuuya unless he abandoned his full brother's egg and it was only through Yuuya's tricks that said brother even had a family to begin with...and that brother was none other than Sakuya. In other words, Sakuya's "father" would have had him thrown away were it not for Yuuya actually caring about him and, as Yuuya points out, he would disown his "son" in a heartbeat if he ever found out about this.
Break the Cutie/Break the Haughty: In the Bad Boys Love route. He finds out that he's not the true heir of the Le Bel family and that Yuuya is in fact his full blood brother, which means that he belongs to the very same mixed noble-common bloodline that he was taught to despise all his life. And this is just before Yuuya dies in front of him from the wounds he got from saving his life.
Comedic Sociopathy: In the drama CDs and the manga, he reacts to being annoyed by other characters not with angry tirades and sometimes sputtering silence as in the games, but rather with angry tirades and by attacking them and dropping them down pits. Particularly Yuuya. When he and Ryouta talk to Shuu and annoy him or are told he wants some kind of price, Sakuya always suggests taking it out of Yuuya.
Fallen Prince: In the extended ending of his route Sakuya has to live with Hiyoko. This is because his father kicked him out of the house because Sakuya wanted to pursue his dream as a musician rather than become the Le Bel family heir.
Fantastic Racism: Treats everybird who's not Shuu or of pure blood like trash. Especially his half-brother Yuuya.
Fantasy-Forbidding Father: He wants to be a musician, but his father has taught him that such ambitions are for peasants, not noblebirds. If the protagonist romances him, he decides to follow his dreams - and is cast out of his house and forced to live in her unheated cave.
Freudian Excuse: He's a Jerkass racist because it's what his father raised him to be ever since birth. As a child he was far more open and kinder, but to his father all the commoners he wanted to associate with were worthless beings.
The Good King: Not a king or prince himself, technically, but raised as the heir to a considerable degree of authority. Despite his pompous, elitist nature when he learns something about The King in Holiday Star he is incensed and gives a lecture about the duties of a king that has the other characters saying Sakuya would be good at it.
Hidden Depths: Wants to be a musician and is surprisingly humble in this ambition. Competent in a crisis. In Holiday Star we also see from his handling of Albert that he's really very canny.
Humble Goal: Not only is his own ambition simply to be a musician and perform for others, he's the one impressed if Hiyoko's Tanabata wish is to become an artist instead of ruling the world.
Idle Rich: If Hiyoko joins the student council, she can bully Sakuya into helping clean the office at the end of the semester, which ends with Hiyoko having to teach him how because he's never done his own housework before. He's actually good at it!
Jerk with a Heart of Gold: Despite acting like a stuck up jerk, he does in fact care about those around him and is willing to help others out without much complaint as long as he's the one in command of course.
This short story from the official fanbook boils down to "These commoners trying to help each other are so stupid it's a joke. I'm going to have to go out of my way to help them."
Pet the Dog: Hates being around his brother, but in Chapter 11 of the manga, after Hiyoko tells him she saw Yuuya digging through the trash and speculates that he's fallen on hard times, he actually seeks Yuuya out and shoves a basket of food at him.
"Take this and go. That is, I don’t want your thanks!"
Poirot Speak: Lets slip a "Tu dis des balivernes!"note "You speak nonsense!" during a stressful moment.
"A king's duty is not to indulge in sloth and indolence! The future will come, yes, and we do not know what tragedies it may bring, but a king's duty is to stand proudly forth and do battle with them!"
Switched at Birth: Yuuya swapped his stepfather's egg with his dead father's egg containing Sakuya so that his brother could have a family and a home instead of being thrown away on his stepfather's orders.
Too Clever by Half: Yuuya notes while preparing to break into a room that Sakuya has set up extensive security.
"But this is him I'm dealing with. It'll look like sneaking in is going to be hard, but knowing him he'll have overlooked something obvious..."
"Well Done, Son" Guy: He's so devoted to his father that he has trouble even considering that his father's prejudiced opinions about non-pureblood birds might be wrong or that he might be happier doing what he loves over taking his father's place. It's made even more painful when he learns in the Bad Boys Love route that the father he's been obeying all his life isn't even his real father.
White Hair, Black Heart: In his human portrait. It's actually light blue, but Sakuya's stand-offish personality qualifies him for this trope.
Beneath the Mask: Yuuya is very forward and comes across at first as ultra confident and cheerful. If you choose to pursue him, follow the BBL route, or play the sequel it becomes increasly clear that this is mostly a front and he is not nearly as indifferent to criticsm or as self-assured as he usually acts, he can be very self-deriding, even despairing on the occasions he lets the mask slip. Lampshaded by both Hiyoko and Yuuya himself at times.
"I already know you're not completely made up of cheap pickup lines and flashy foppishness"-Hiyoko
All this time I've just been trying to look cool so no one will realise what's going on inside. But what's wrong with putting on a little show?" -Yuuya
Berserk Button: He's the first to admit that Sakuya's kind of a pain, but just about the only thing that can break Yuuya's cool is a genuine threat to his little brother.
Big Brother Instinct: He genuinely cares for Sakuya in spite of being treated like dirt by him. To the point where he defied his stepfather's orders to abandon his egg and switched it with his stepfather's own egg instead so that Sakuya could have a family and home. He shows lesser aspects of this, wanting to protect other characters, throughout the rest of both games.
In Holiday Star's TDTNS chapter he even serves this role for Ryouta when he must counsel Ryouta's insecurities about beloved childhood friend Hiyoko possibly abandoning Ryouta in favor of somebirdie else's romance.
Bi the Way: "I'm always straight in love...well, most of the time."
Butt Monkey: In the manga and especially the drama CDs.
Chivalrous Pervert: He tells Hiyoko among other things that doves reach sexual maturity after only one year and interprets the act of looking at nest-building materials in a specific way.
Cool People Rebel Against Authority: In game it seems like he's seen as possibly the coolest member of the cast, an 'infamous studmuffin' who often doesn't even go to class. Then there's the fourth chapter of Holiday Star.
Are you going to follow his orders just because he's the king?
The Cracker / Playful Hacker: Apparently a genius-level computer hacker, with skills that his brother believes were honed in secret over many years... pirating pornography on the internet. It's more probable he learned it working for the Dove Party.
Cruel to Be Kind: From his perspective, trying to warn Hiyoko off by telling her about how pursuing him is dangerous.
Handsome Lech: For example, there is the way he interprets the act of shopping for nest-building materials.
Hidden Depths: He loves his brother so dearly that he'll throw everything away for him, and he wants to protect people from Shuu but has been blackmailed into silence, and he's so secretive he has trouble telling anyone things that are important to him. He'll help selflessly if someone's in danger. Incredible guilt weighs him down and bears him onwards, trying to make up for it.Lampshaded once by Hiyoko, who says that she already knows there's more to him than cheap pickup lines and flashy foppishness.
Higher Understanding Through Drugs: When the rest of the cast is trapped in a dream and he enters it to save them, the ghost controlling the dream hides one from him until Leone injects Yuuya with some psychotropics. Yuuya is completely lucid despite noting that he's high, and is able to have a verbal confrontation and find the hidden person.
Idiot Feather: In the manga, they lampshade the problems of having three white fantails in the cast. Yuuya's distinguishing accessories in bird form are his glasses and an ahoge.
Informed Attribute: He's said to be the School Idol, but this is rarely evident. This gets pointed out and he's asked if he's really "got it", to which he responds, "A man who's 'got it' never says he does."
Major Injury Underreaction: In both BBL and Holiday Star. BBL is the scalpel, which he knew was poisoned, Holistar is a tank shell he took / shoved Hiyoko out of the way of. In the latter case he brushed off the injury and his primary concern was if she was okay, but apparently he was burnt too badly to stand.
Meaningful Name: "Yuuya" can be written with characters meaning "wealthy one", which doesn't fit, but it may also be written with the characters meaning "tenderness; excel; superiority; gentleness" or "masculine; male; hero" for 'yuu' and "all the more; increasingly" (ya)
Name of Cain: The Fantasy AU version of him is named Cain Reprobus.
Not So Stoic: He's got a weird, friendly, cheerful kind of stoicism, but it very nearly never breaks.
Obfuscating Stupidity: When you interact with him outside his route and BBL its seems like he's like a relentless flirt who doesn't care about school. However it's later revealed that he's a Dove Party agent spying on Dr. Shuu to obtain intelligence on Shuu's development of bioweapon technology!
Offing the Offspring: The Bad Boys Love route reveals that he was ordered by his stepfather to throw Sakuya's egg away because it had been hatched between his mother and old father. Instead, he waited until his mother laid an egg with his stepfather, switched that egg with Sakuya's, and smashed the other egg so that Sakuya could survive.
Oh Crap: If Hiyoko tells Doctor Shuu that Yuuya was lying about not looking through Shuu's desk, Shuu thanks Hiyoko before kicking her out of the infirmary, since he needs to discuss this with Yuuya... alone. Yuuya's reaction to being cornered by the angered creepy doctor? "...Shit."
Poisonous Friend: More cynical and willing to do shady things than he initially seems.
The Pollyanna: Most of the other characters trapped on Holiday Star need some persuasion or encouragement to overcome their personal problems. However, Yuuya is immediately able to accept his personal troubles and look optimistically towards the future. Yuuya wholeheartedly rejects The King's offer to ease his guilt for murdering his unborn half-brother, leaving the pain-averse King in shock.
The Resenter: Despite his love for Sakuya, there are times when Yuuya shows condescension or a trace of resentment. In one of the drama CDs Shuu almost kills someone, to the dismay of the other characters. Sakuya tries to defend him and Yuuya, striving to save the life in danger, snaps, "Why don't you try showing some concern for others once in a while, Sakuya?"
Stepford Smiler: Always - always - comes off as either relaxedly cheerful and careless, or professional. Even in BBL, until the end. In Holiday Star there's the option to have a shrine visit with him in his pseudohuman ICPSS form, and in it he smiles through greetings, smiles through flirting, smiles through being insulted, smiles through starting to reveal something and then through dissembling about it, smiles through showing a bit of Self-Deprecation bordering on despair, and has a slightly different smile when encouraged by Hiyoko.
"All this time I've just been trying to look cool so no one will realize what's going on inside. But what's wrong with putting on a little show?"
Taking the Bullet: In the first chapter of Holiday Star he takes the tank shell and manages enough of a Diving Save that he's just burned and not dead, but it's still incapacitating. And in BBL he takes the scalpel.
You Are Better Than You Think You Are: After he makes several deriding comments about himself (if you choose to meet with him at the Shrine in Holiday Star), Hiyoko more or less says this to Yuuya word for word.
"I think you're a better person than you think you are, Yuuya! Sakuya and the doctor are always chewing you out, but you shouldn't let that get you down. Just do your thing and be yourself."
This quiet dove spends all his time in the library.
Animal Stereotypes: He's a mourning dove, so naturally he's not going to be the cheeriest creature around.
Bad Powers, Good People: The "Bad Boys Love" route indicates that this was true of Nageki when he was alive; he was the carrier for a fast-acting lethal-to-humans virus, and committed suicide to stop Dr. Shuu's attempts to weaponize it.
Bird of Mass Destruction: He turned out to have a disease that killed any humans who came close to him. However, he ended up killing himself when he couldn't stand being used to make humans die anymore.
Brooding Boy, Gentle Girl: During Nageki's route, Nageki is the brooding boy and Hiyoko is the gentle girl... though she's far more willing to act the thug than he is, she's also much more cheerful and open.
But Now I Must Go: If Hiyoko pursues him, then her love for him allows Nageki to proceed onto the afterlife at the end of his route.
Can't Live with Them, Can't Live without Them: He describes the other students as this to The King when he's trying to convince The King to make friends rather than hide in the secluded fantasy world of Holiday Star. The other students are loud, active nutcases and being around them tires him out, but he likes them and is happy to have them.
Chekhov's Gunbird: See all the spoiler-tagged tropes here? Only about half of them are even for his route, and even those only at the very end. The remaining spoiler-tagged tropes are found outside his route or in the Holiday Star sequel.
Dead All Along: This helps explains his aloof behavior and his tendency to only be found in the library.
Deadpan Snarker: Can get this way if his peers are acting exceptionally silly.
Ghost Amnesia: His relationship with Hiyoko during his route helps him remember that he's dead and that he died by suicide.
Ghostly Chill: The library is uncomfortably cold during the winter not because of the faulty heating, but because a ghost resides in the library.
The Hero: He is this in Holiday Star's last two chapters, with Hiyoko as his Lancer.
Heroic Sacrifice: He planned on doing this in Holiday Star's TDTNS. He would burn up again along with The King's lighthouse so his friends would be able to go home. However, Hiyoko saves him from the fire.
He also did set himself on fire in the backstory to stop Shuu using him as a weapon to kill humans. After human extremists attacked Hatoful House and killed all but one of Nageki's foster-family there.
Hidden Depths: He shows a degree of kindness and sympathy towards numerous characters in Holiday Star, including the King as he notices the similarities in their circumstances and backstories. His willingness to commit to Heroic Sacrifice indicates that while he doesn't express himself well, he is passionate and protective.
Hikikomori: He's almost always found in the library, and always seems upset whenever Hiyoko suggests leaving the library or at least doing activities outside. However, Nageki isn't always in the library by choice, since he is trapped here as a ghost.
Ill Bird: Due to him harboring a human-killing virus that could thrive only in a weak immune system.
Loners Are Freaks: For some reason he never interacts with any of the other students in the library and at one point seems to actively avoid sitting at the same tables as them. This is because the other students wouldn't be able to see a ghost anyway, let alone interact with him.
Not Afraid to Die: He displayed this while committing suicide originally. In Holiday Star's TDTNS Nageki also displays this when he must die in a fire again to destroy The King's lighthouse.
Older Than He Looks: He says he's a freshman and he looks like the youngest student Hiyoko can pursue romantically. However, he actually committed suicide as a freshman five years ago. He just still looks like a freshman as a ghost because that's the age he died at!
Ontological Mystery: According to Document 2 in the archives of the original game, Nageki's constantly existing in one as a ghost who forgot his memory.
Nageki: "I feel uncomfortable. Where did I come from? Where was I born? The fact that I am trapped in here is the least of the mysteries plaguing my mind. Nervous. I'm nervous."
Orphan's Ordeal: As an orphan of war, he doesn't even remember what his birthparents looked like.
Our Ghosts Are Different: Only those with pure hearts can see this ghost. So far this includes Hiyoko, Ryouta, Okosan, and Anghel. He can also move vertically throughout the area he has died in, but he cannot move far horizontally, so he's restricted to part of the roof, the library, the chemistry lab, and part of the complex underneath.
Patient Zero: BBL route reveals that he originally harbored the virus that Dr. Shuu wants to use Ryuota to eradicate humanity with.
Scary Librarian: He really doesn't like it when the other students make a ruckus in the library, shown especially in the radio play and manga◊. Although he isn't an actual librarian, he does spend the majority of his time there.
Ryouta: "Nageki is a ghost, but he's not evil... I guess he can be scary if you make a mess of the library books, but..."
Self-Immolation: He committed suicide by setting himself aflame so no trace of the deadly virus would remain.
Shown Their Work: Male mourning doves◊ at sexual maturity have iridescent spots of feathers on their throats and green rings around their eyes, just like Nageki's bird photo has. On the other hand, female mourning doves lack these iridescent spots and green rings.
Shrinking Violet: When Hiyoko first meets him, Nageki gives off this vibe before we learn the actual reason why he's seemingly reclusive and anti-social.
Star-Crossed Lovers: On his route, Hiyoko and Nageki's love for each other causes the ghostly Nageki to fade away to the afterlife.
When He Smiles: The ICPSS version of his Shrine visit gives him a handful of expressions, though mostly they're the same sort of closed, disinterested look. At the end of the visit he smiles, and it's very sweet.
Hidden Depths: Doesn't understand everything going on, but in BBL he's unexpectedly kind to a distraught Sakuya, and gives him a priority check by asking why breeding is so important when you have friends.
Innocent Inaccurate: It's speculated on the Bad Boys Love route that he doesn't understand the concept of death, which is why he doesn't fully grasp that Hiyoko and Yuuya can't be simply "rescued" or "chased after".
Beware the Nice Ones: During Holiday Star the blinded Kazuaki serenely tries to strangle Yuuya while Yuuya is trying to rescue him. This causes Yuuya to note that even if Kazuaki looks calm on the outside, he must be pretty messed up on the inside. Kazuaki's backstory revealed in the original game's Bad Boys Love route confirms this, and is expanded upon in the final storyline of Holiday Star, to terrifying effect.
Bunny-Ears Lawyer: His sleeping interferes with his teaching, but he's still a world-famous mathematician, and apparently also versed in physics. Possibly some overlap with Genius Ditz.
Cute and Psycho: In the Bad Boys Love route, it's revealed that the death of his brother Nageki haunts him to the point where he constantly talks to a dark manifestation of his guilt that he believes to be Nageki who holds him responsible for his death. This fully manifests when he learns that Nageki's liver was implanted in Ryouta and approaches Ryouta with a knife, muttering Nageki's name over and over again and about how he needs to take Nageki home with him now.
Cynicism Catalyst: Nageki's death years ago had led Kazuaki to disguise his identity and teach at St. Pigeonation's to get revenge on Dr. Shuu. Additionally, he gets hallucinations of Nageki's spirit guilting him for his death and urging him to commit revenge.
Dead Person Impersonation: According to the guidebook, Hitori encountered a button quail named Kazuaki Nanaki a few months after Nageki's death. He assisted said quail in suicide and then swapped their identification papers, handing over the original Kazuaki's remains as his own.
Dissonant Serenity: Kazauki's interior isn't nearly as calm as his exterior suggests, considering his twisted mental state and emotional turmoil from his tumultuous past.
Distressed Dude: In Holiday Star Yuuya must rescue Hitori, who has been very carefully hidden away by The King so that Hitori would never leave his star.
Dye or Die: After Nageki's death he disguised himself by bleaching his feathers white to pursue revenge on Dr. Shuu as well as evade Hawk Party agents.
Eyes Always Shut: In the game the first time that Hiyoko sees him nodding off she thinks "He sleeps with his eyes open?!". In the manga, though, his bird form is always shown with closed eyes, even when other button quails have normal eyes.
Eye Scream: At some point during his time on Holiday Star Hitori eats his own eyes. Luckily Hitori's eyes are always tightly shut so we never see his empty eye sockets. Considering Hitori's twisted backstory, his self-eye gouging may be an allusion to Oedipus gouging out his own eyes after learning he had murdered his father and married his mother.
False Friend: To the original Kazuaki Nanaki, whose identity he took. As Hitori, he tricked the clinically depressed quail into committing suicide by acting like his best friend and convincing him into making a suicide pact. Of course, Hitori didn't follow through with the pact and let the original Kazuaki die alone.
Heroic Albino: The quail representing his bird form looks leucistic. However BBL reveals that Kazuaki's feathers are bleach-dyed white and Holiday Star reveals that Kazuaki isn't nearly "heroic" as his calm exterior suggests.
Hidden Depths: And how. There's a reason Kazuaki has so many spoiler-tagged tropes in his section!
Magical Bird Warrior: He becomes one of these in Holiday Star's Absolute Zero chapter to protect the school from Tohri blowing it up with his lasers.
Meaningful Name: Nanaki written as 名無き in Japanese means Without a name’, and Hitori written as 一人 means ‘Alone’. Left alone, he stole the other quail's name.
[No Doubt The Years Have Changed Me: In the Bad Boys Love route, he reveals that he's actually Nageki's brother Hitori who was presumed to have died in the fire Nageki created during his suicide attempt. And based on a throwaway observation from earlier about him smelling like chlorine, he most likely bleached his feathers to prevent Doctor Shuu from recognizing him.
Orphan's Ordeal: As an orphan of war between the birds and humans, he was the older brother figure for all the other younger orphans at Hatoful House. His gradual, tragic losses of all of his orphan-siblings cause his subsequent descent into madness and revenge...
Removed from the Picture: If Hiyoko is on Kazuaki's route, she finds a photo dropped by him that has the photographed bird almost completely marked out. Which, in the Bad Boy's Love route, we learn was probably a photo of his dead brother, Nageki.
Scarf of Asskicking: Portraits of Hitori as himself show a red scarf as his favored accessory. After he assumes Kazuaki's identity, he wears the latter's beige wrap instead.
Stepford Smiler: Assuming he often shows the smiling facial expression of his human portrait (or at least the bird equivalent) around others, Kazuaki may be this. If he indeed smiles even if he isn't happy on the inside, then Kazuaki is a stepford smiler of the Depressed and Mentally Unstable types.
Tareme Eyes: He is a kindly and calm math teacher. His poor sleeping habits may also contribute to his human portrait's droopy-eyed appearance.
Shuu: "You could tell from the start that I was dangerous, couldn't you? And yet you came to see me, again and again. Very... assertively."
Axe Crazy: Well, his introduction does outright mention his creepy nature and bad reputation among the student body. Though you only learn the full extent of his terrifying nature near the end of his routes and during BBL.
Blind Without Them: According to a Radio Q&A in Holiday Star, Shuu is blind and helpless without his glasses.
Big Damn Heroes: Despite being a creepy jerk at all other times, he manages to do this twice in Holiday Star. Though Shuu was ultimately motivated into these actions by his fondness for Ryuuji Kawara someway or another.
He uses a gas bomb to cause Miru and Kaku to break out into a severe allergic reaction while leaving everyone else unharmed. This stops Miru and Kaku from using their tank to blow up the Le Bel mansion.
While our heroes are about to be overtaken while battling the monstrous King, Shuu throws a container of tranquilizer at the King to temporarily impair him neurologically. This allows Nageki and Hiyoko to safely proceed past the King towards his lighthouse.
Creepy Monotone: Sakuya notes that he rarely has any inflection in his voice.
Creepy Physical: He wants to examine your insides most intimately once he's done with your pretty head.
Defrosting Ice King: As seen in Holiday Star, Ryuuji Kawara is the only character who even has the slightest possibility of accomplishing this.
Frankenstein's Monster: During BBL he created a variation of one of these named Labor-9 to antagonize our heroes. It looks like a monstrous cyborg-scarecrow with mismatched limbs and a bloody burlap sack face. It can only vocalize in grunts. And Shuu implanted the deceased Hiyoko's brain into its head to make it function.
Hidden Depths: Despite his aloof loner disposition, Shuu is still driven by the memory of his deceased colleague/mentor.
Herr Doktor: Shuu isn't of European origin at all. However, the vaguely Germanic nickname Anghel gives Shuu, "Dark Sorcerer Wallenstein," nicely highlights the latter's sinister mad scientist nature.
Hollywood Atheist: Why does the diabolical and coldly scientific Shuu make a shrine visit during New Year's day in Holiday Star? Not to pray to any deity, but to find a rotting corpse to examine!
Hiyoko: "But what are you here for, sir? Are you making a New Year's offering?"
Shuu: "No. I feel no need to plea to hypothetical gods for help."
I'm a Humanitarian: At the end of his route it's revealed that he cooked Yuuya into something resembling a roast chicken, which he then gifted to Hiyoko to eat for Christmas. Also during Holiday Star he tries to trap and cook Miru and Kaku and others while on the titular planet.
Jackass Genie: In the Bad Boys Love route, it's revealed that he promised Ryouta's father that he would fulfill his son's wishes if he could, and Ryouta told him that his wish was for humans and birds to live in peace with each other. Except that his idea of making humans and birds live in peace is to kill all humans — after all, humans and birds can't fight each other if there are no humans left!
Love Makes You Evil: It's heavily implied in the Bad Boys Love route that he was in love with Ryuuji Kawara, which is why he takes his promise to Ryuuji to fulfill the wishes of his son Ryouta very seriously to the point of planning extermination of the human race. Also, it's quite possible that he wasn't as unhinged as he is now until Ryuuji died.
Angie Gallant: All he has done, he has done for love. HORRIBLE HORRIBLE EVIL UNEARTHLY INFERNAL LOVE.
Mad Scientist: Doctor Shuu wants to feed steroids into Oko San just to see how his body will react to them. It turns out that he is a researcher for the Hawk Party.
Mummies at the Dinner Table: At the end of his routes he murders and dismembers Hiyoko's body; however, he keeps her head in a jar out of affection. As he flees from the St. Pigeonation's he brings the jarred head with him and asks her if she loves him. The head's "answer"? "YES YES YES"
Nightmare Fetishist: Shuu has a deep fascination of the macabre. During certain points in Holiday Star he mentions how delightful it would be to find demons or rotten corpses to examine!
Shuu: "Demons...? If there are any here I would love to take one home to examine."
Seldom Seen Species: It's likely that Hatoful Boyfriend is the first time players have ever encountered a Chukar Partridge character in media. Unfortunately this may mean players will then associate Chukar Partridges in general with a cold, calculating, murderous antagonist...
A Sinister Clue: He uses his left wing to hold the cleaver to dismember and kill Hiyoko.
Subverted and justified; his right wing was injured and crippled. The implication is he'd favor it normally.
A literally bleeding-heart bird who only appears in the full version of the game and proclaims himself to be a fallen servant of God.
Aluminum Christmas Trees: People in the Let's Play thread were convinced that the photo used for his bird form was either a Photoshopped hoax or a bird that had been shot. Bleeding-heart doves are in fact real, and the red stain on their chest is natural.
Awesome McCoolname: The name "Anghel Higure" literally means "crimson scarlet angel." The way "Higure" is rendered involves the characters for two different shades of red.
Bandage Boy: His IPCSS portrait depicts him with bandages covering his left eye and chest.
Bow and Sword, in Accord: Not that we really get to see, but his main weapons are a bow called Holy Slasher (an arrow charm) and the Holy Spear Sae'krom (a mapping pen) which in official art looks more like a sword.
The Chosen One: He's convinced that Hiyoko is some reincarnated deity named Edel Blau.
Cloudcuckoolander: Manages to make Oko San's pudding obsession come off as downright mundane in comparison.
Do Not Call Me Paul: He flips out when Hiyoko attempts to call him by his real name Yoshio Akagi and claims that using "the forbidden name" will cause great evil to be unleashed. Hiyoko doesn't seem to take his claims very seriously, though, and in fact thinks his real name is very nice. In a drama CD Sakuya uses his name and Anghel flaps around on the ground crying out. It can be seen in Holiday Star that he doesn't mind his mom using that name, though.
Dynamic Entry: His entries tend to be accompanied with the shattering of glass windows. Lampshaded by the heroine.
Foreshadowing: If players are perceptive enough to notice it, Anghel makes a fleeting one at the end of his New Year's shrine visit with Hiyoko in Holiday Star. It pertains to The King's Holiday Star becoming a threat during the lunar eclipse at the end of their sophomore year. The Holiday Star seems to be a pretty and peaceful dreamworld. However, it is actually a twisted Eldritch Abomination hive mind that traps wandering souls who are troubled and weak at heart.
Anghel: (to Hiyoko) "A creeping dread, a growing malaise...or perhaps, a light. ... A world is but the light reflected from a fragment of the broken mirror. The fragments write out the destiny of every star in the heavens. Is your Azure Soul satisfied with the world and the fate you see before you now? Or perhaps it has been charmed by the fate written by a different shard of the mirror. If that is the case, then I shall..."
Large Ham: "You must not say the forbidden name! It shall open Pandora's Gate, and bring about the End of All Things!"
Leitmotif: This. Besides Anghel's appearences, this song is notably only played when something else strange is happening.
Mad Oracle: A lot of the things he alludes to in his warped fantasy metaphors are things he has no way of knowing, such as Nageki's past, Yuuya's treachery, and/or the threat of Holiday Star.
Maybe Magic, Maybe Mundane: The pheromones would certainly seem to explain why his route ends the way it does... Some fans believe he has the ability to sense disease, and thus Himnesia is the Charon Virus, which Shuu was cultivating in him. Holiday Star heavily implies that it's more than delusion, though since his power is used for a laser, and for stopping said laser. He may actually be a Reality Warper.
Mukokuseki: Luzon bleeding-heart doves are from the Phillipines, and Sakuya makes some racist comments about Anghel being Filipino (which are later innocently echoed by the heroine). You wouldn't know it to look at his human-style portrait.
Mushroom Samba: It's revealed on the Bad Boys Love route that he secretes hallucinogenic pheromones, which explains why he's so nuts.
The Nicknamer: Refuses to call anybirdie by their given names, or any place by its given name, unless he absolutely has to. Except for his own, the names he comes up with are always much more elaborate than their given names.
Obfuscating Insanity: Sort of. The heroine seems to suspect this at a few points; she observes that he seems to be making an excuse to get her to take his shift working at a festival, and when she tries to give him beans she believes that he's rushing her out into the hall first so his classmates won't tease him for having a girlfriend. He really does have a warped view of reality, but he's more aware than he seems. In the BBL route somebirdie observes that he may babble madly, but he's really fairly intelligent and insightful, and he can be pushed into using the names the "ignorant many" use for a few things he has to identify (the clinic and the heroine).
In Holiday Star Anghel may even be obfuscating sanity to his own mother. When she calls for him to eat dinner or asks him what his plans are for the evening, Anghel always replies to her in normal sentences lacking his usual Purple Prose.
Secret Character: He's sort of this, as he doesn't appear in the game unless you've completed one of the routes requiring you to work in the infirmary (Shuu's or Yuuya's) and made a certain wish at Tanabata.
Seldom Seen Species: Anghel Higure may be the first time players have ever encountered a species of bird whose plumage make it seem like it's bleeding from its chest.
Spell My Name with an S: The English translation spells his name as Anghel, but many people call him Angel instead.
Probably because this was how fans originally romanized his name, before the official translation changed it.
May count as a bilingual bonus as Anghel means Angel in the Filipino language, his land of origin.
Tsurime Eyes: His one uncovered eye in his human portrait is this shape.
Ryouta's father, who died when he was young. He worked in the same research laboratory as Shuu, then known as Souma Isa, and died from a disease he contracted on a study trip abroad. Whilst alive, he was head of the biology department.
The Drifter: Appears in Holiday Star's TDTNS chapters as "The Migrant" to give advice to our heroes when they need it most. Turns out that he and every other deceased birdie soul must aimlessly migrate throughout the galaxy in order to eventually be reborn on Earth.
Eccentric Mentor: May have been one to Shuu/Isa while he was still alive. He also acts as one to our heroes while they are stuck on Holiday Star. Finally he even becomes one to the distraught King when Holiday Star is annihilated and The King has no choice but to join every other deceased birdie and ride the galactic railroad throughout the afterlife.
Fatherly Scientist: He was this towards the lab experiments Miru and Kaku while he was alive. He took care of them while the rest of the scientists wanted to euthanize them once they outlived their usefulness for scientific research.
The editor-in-chief for Golden Weekly, a manga magazine. He scouts Anghel as a potential contributor to his magazine, citing his artistic potential. He previously worked in the same research laboratory as Ryuuji and Isa, albeit in a different division (the Second Optical Weapons Division). Disgruntled with being constantly overlooked in favor of Isa, he eventually left in search of somewhere that would appreciate his talent more.
Agent Peacock: While his near-constant narcissism and hamminess are a bit ridiculous, he is very good at building and operating foreboding laser technology
Animal Stereotypes: The bird with the ornate, brightly colored feathers is very showy and full of himself.
Astonishingly Appropriate Appearance: His gijinka reflects his plumage in great detail, from the color and decorations in his hair to his eyes to his wardrobe. The other gijinkas might reflect the character's real forms in various ways but it's never consistent - hair doesn't always match feathers, same with eye colors, and most characters keep to uniforms.
Mad Scientist: He creates a laser cannon using [[spoiler: Anghel's powers and the will and drive of fanboys and fangirls.
Narcissist: Believes himself to be special and refers to his creations as 'masterpieces'. He holds a grudge against Shuu because of this, looking down on him yet constantly frustrated in his efforts to upstage him.
How the Characters Stole Christmas]]: This is the main plot within their debut chapter. The twins love Christmas so much that they inadvertently ruin Christmas for everyone else by stealing their Christmas trees.
Killer Rabbits: These cute creatures won't stop at using explosives and tanks to get the Christmas trees they want!
The Medics: They tend to Sakuya's injuries during the battle against The King's monstrous Increased form. Likely they learn these skills from living around Shuu and his infirmary throughout Holiday Star.
Series Mascots: Before the English version of Holiday Star was released, the twins seemed to be the mascots for this game. It helps that the twins have an obsession with Christmas and that their appearances on promotional artwork have minimal spoilers for content deeper within the game.
Someone to Remember Him By: Shuu keeps the twins under his care since Ryuuji Kawara took care of the twins himself while he was alive. Shuu would never be a nurturing type of birdie otherwise.
Tagalong Kids: They serve as these after Holiday Star's first chapter where they made their big debut.
Verbal Tic: Just as Okosan's dialogue consists of translated coo's, the twins' dialogue consist of translated phrases of "Merry Christmas!"
The King/The Original Kazuaki Nanaki
Species: ??? (was a King Quail like Hitori Uzune when alive)
The King appears prominently in the last two chapters of Holiday Star, which are each quite long. During a collective dream, our heroes meet The King on the titular fantasy world of Holiday Star that he rules. Needless to say, just like Nageki and Kazuaki above, this character requires many spoiler tags in his section.
Adorkable: The King is awfully timid for royalty. Even the AU short side stories where The King is still alive as Kazuaki show him with this personality.
And I Must Scream: This was along the lines of what Kazuaki was thinking when Hitori was leaving him to die alone from a drug overdose in a false suicide pact.
Kazuaki: "Someone... help me...!"
Angrish: His storybook to Hitori consists of angry pulsating scribbles, several blank pages, and ends with the quote "You lied to me" and an animation of a quail (presumably Hitori) falling into enormous flames. In contrast, all the other storybooks The King wrote to the birds at least have and a storyline.
Assimilation Plot: After a while every visitor to Holiday Star will not only be unable to leave, but they will also lose their individual identity and become one with The King's hive mind. To The King if everyone is the part of one whole, no one will need to quarrel among one another.
Book Ends: What did the highly suicidal Kazuaki think during the depths of his depression, right before he met Hitori? "Someone, help me...". And what did the dying Kazuaki think right after his friendship with Hitori ended, who abandoned him in the false suicide pact? "Someone... help me!"
Despair Event Horizon: This is what Kazuaki was experiencing after his only friend Hitori left him to die alone in a false suicide pact.
Eldritch Abomination: Before he was horribly betrayed by his former best friend, The King was once an emotionally unstable button quail named Nanaki Kazuaki. He is now a monstrous Hive Mind that sprouts multicolored extra heads when angry, kidnaps our protagonists to his Fisher Kingdom, and tries to absorb any souls he encounters, living or dead, out of desire for eternal friendship without betrayal.
Evil Former Friend: Turns out that The King is the corrupted soul of Kazuaki, the betrayed former friend of Hitori.
Foil: To Nageki. And to an extent, imposter Kazuaki aka Hitori. The massive number of spoiler-tagged tropes in their sections isn't the only thing they have in common...
For Happiness: He traps wanderers onto his star so they will be perpetually happy and never again come into contact with the world's evils.
Founder of the Kingdom: The King created the Holiday Star that he rules himself. He was the first troubled wandering soul who got off the galactic railroad and wanted to escape the hardships of reality via a static fantasy world.
Fragile Flower / Nervous Wreck / Shrinking Violet: The timid King seems perpetually scared or about to cry, unless Nageki and Hiyoko can help solve problems within his kingdom. And he had this personality when he was alive as Kazuaki as well.
Nageki: (to The King) "Why would you start crying just because it's raining?"
Hiyoko: "The heroine in a J-Pop song or shoujo manga might do something like that. Maybe The King is a delicate maiden at heart? Don't worry, your highness! I will protect your fragile heart from the cruel weather!"
Friendless Background: Before Kazuaki met Hitori he had no friends due to his debilitating shyness. He also viewed all other birdies as cruel beings in general.
Glamour Failure: Hiyoko notices that for the split-second The King becomes exceptionally emotional, his head becomes deformed and discolored while sprouting out another such similar head. This is one of the first clues that's something's not quite right about him...
The Good King: The citizens of Holiday Star advocate The King as this. However, it turns out that all the citizens are simply projections of their former selves from before they became part of The King's hive mind, so...
Hates Being Alone: He gets nightmarish and violent if any of his visitors threaten to leave his star. Also while he was alive as Kazuaki he was very clingy toward his only friend Hitori.
The King: "THE KING WILL NOT LET YOU LEAVE!"
Healing Factor: In his One Winged Angel Eldritch Abomination form, each time one of his elongated heads is taken out, several more take its place akin to a Hydra. This is because Holiday Star is a Hive Mind made up of countless lost and troubled souls.
Heterosexual Life-Partners: He and Hitori seem pretty close to being this, in the alternate universe shown in the sidestories and supplementary manga. Arguably they were also this in the canon universe, but it didn't last.
Hidden Depths: The King's unhidden tropes indicate him to be an overall cowardly and nonthreatening character. However, during the climax Nageki confronts The King's true monochromatic, cowering form at the lighthouse. If Nageki chooses the wrong stone to replace the one that The King took from the planisphere, then the player gets a Nonstandard Game Over. The King reveals that the garnet and lapis lazuli are fakes, and are safeguards against Nageki ever using his planisphere to destroy The King's lighthouse. Likely The King sent Nageki and Hiyoko on the sidequests not only to remove threats in his kingdom, but also to build their trust so he could eventually remove a gem from Nageki's planisphere after having given Nageki two of his own fake gemstones. This shows that even if The King appears to be a cowardly and pathetic character, he can be canny and manipulative as well.
Hikikomori: In the depths of his depression Kazuaki refused to leave his bed at home for school or anything else.
Hive King: All of the "citizens" on his star are wandering souls that he eventually absorbed into his consciousness. Through any of them The King can project his physical or mental self.
Hiyoko: "In other words, this whole place is basically a cult of loneliness and crazy peer pressure!"
Hope Is Scary: Once his star is destroyed, The King qualms against joining his ex-subjects and the Migrant in traveling the night sky because he doesn't want to be reborn into a life of misery and suicide again.
I Cannot Self-Terminate / Suicide Pact: Kazuaki was suffering from clinical depression for quite a while, yet he could never get himself to commit suicide. Eventually Hitori tricked Kazuaki into committing suicide by pretending that he was a best friend making a suicide pact with him.
I Know What You Fear: He knows the personal issues that torment each of the visitors to his star. He uses this ability to convince his visitors to stay at his star to remain happy and safe.
Leitmotif: This. At least, when he's in a good mood and in his non-Eldritch Abomination form...
Loners Are Freaks: The King's isolation immediately after his death may have been the reason why he created Holiday Star in the first place.
Madness Mantra: While Kazuaki was alive and suffering from severe clinical depression, he constantly thought to himself, "I want to die. I want to die. I want to die."
When The King transforms into an Eldritch Abomination and is desperate to get Nageki and Hiyoko to join him on his star, he constantly utters to them something along the lines of, "The Kiiiing s-s-said, beeeeecome oneee with usssss..."
From Nobody to Nightmare: While alive, he was a timid, severely depressed button quail who believed he was nothing and couldn't even get himself to leave his apartment. After his untimely death, he is now an emotionally unstable Eldritch Abomination who seeks to absorb any other soul passing by into his miasma in order to fulfill his desire for eternal friendship without betrayal. He's the undead lord of a dead kingdom, indeed.
Nonstandard Character Design: Almost every other bird character is represented by a real-life bird photo. On the other hand, The King is a stylized watercolor drawing of something resembling a bird. This serves to match him with the watercolor drawing of a surreal kingdom which he rules.
One-Winged Angel: His monstrous "Increased" form involves him sprouting out multiple elongated and discolored heads. He attacks the heroes in this form when they threaten to leave his star.
Revenge: The King keeps Hitori very well hidden away in his kingdom compared to the other birds. Why? Hitori had wronged The King very badly when he was still alive as Kazuaki...
Rubber Bird: He can shapeshift his form based on his emotions. Sometimes, those forms are quitescary. This ability allows his One Winged Angel Eldritch Abomination form to absorb impacts from attacks with little to no harm. If Hiyoko is reckless while fighting him, she can get stuck into him and promptly absorbed into his twisted hive mind!
Sensitive Guy and Manly Man: While sensitive guy Kazuaki is timid, insecure and somewhat flighty, manly man Hitori is assertive, self-confident, and proactive, though also nurturing. The fact that Kazuaki is a literature student and Hitori is a math/science student might also fit the stereotype.
Shout-Out: The King seems at least partially inspired by The King in The Little Prince. Both are royalty who live on their own planets. They both seem lonely since they don't have any real subjects, yet their own selfishness is what ultimately drives their visitors away.
Spell My Name with a "The": Most characters, including himself. Aside from Yuuya, all of them capitalize both "The" and "King" each time, too.
Surprise Creepy: When we first meet him, The King is a comical character who cries easily and relies on Nageki and Hiyoko to resolve minor disturbances in his kingdom, one of which is the possibility of rain on his castle. However, later we see brief flashes where he grows a second discolored and deformed head... and the rest is in all his spoilered tropes.
Sweet Tooth: During the AU short side story where St. Pigeonation's faculty give a tour of the city, Kazuaki seems more enthusiastic about showing off the sweet shops rather than the actual tourist attractions and monuments.
Voice of the Legion: The King gets this after transforming into his monstrous "Increased" form.
Was Once A Bird: Once The King is revealed to have a monstrous form, Nageki asks The King to tell him his backstory. The King was once a normal King Quail named Kazuaki Nanaki. Hitori Uzune, another King Quail, acted as Kazuaki's best friend and tricked Kazuaki into committing suicide so that he could steal his identity. The King we see here is Kazuaki's soul which became embittered and corrupted after death.
Well-Intentioned Extremist: He believes that trapping and absorbing wanderers to his star will protect them from the evils in the world, as well as keep them perpetually happy.
What's Up, King Dude?: Nageki and Hiyoko can walk into The King's throne room whenever they please. Justified since most "threats" in the kingdom are neutralized by The King absorbing any unique individuals into his consciousness.
Magic Antidote: In the full version of BBL he finds a poisoned Yuuya on the brink of death and gives him an antidote. It does appear that Yuuya wasn't up to normal functionality for months or more, though.
The Stoic: Always seems collected and calm. Yuuya calls him "unflappable".