A highschool student who lost her parents and older brother in a plane crash. Full of grief, she heads to the wizard K, who is said to fulfill any wish his client has. But K cannot fulfill wishes that involve life and she cannot leave until she has wished something, since she saw his face, so now she's made a maid and assistant in his 'office'. She's a hothead, easy to anger and can't stand selfish people.
- Berserk Button: Insulting her family, she even got into a fight with a schoolmate over it. Being a complete jerk, which makes her easily angry with K.
- Fantastically Indifferent: After meeting a sprite the size of a thumb, a wizard who is stalked by the sun and meeting a race of aliens that can turn into healing flowers, Jin is practically immune to the shock of meeting a 150-year-old vampire.
- It's All My Fault: Several throughout the story.
- She blames herself for causing her family's death, by wishing the plane would crash. It wasn't her fault.
- She blames herself when, after forcing K to take on a client's wish, he tries to commit suicide, because his client's wish was to die. It wasn't her fault, it was a miscalculation on Li-Hun's part.
- She blames herself for persuading her friend to make a wish to K, which results in her friend's father dying.
- I Wished You Were Dead: Angry at being left behind because of a cold, Lyu-Jin thought that 'the airplane should just explode' and then learns that the airplane her family was on really did explode. A flashback shows that she told her brother that he should 'go ahead and die', shortly before they left for their flight. And in her anger, Jin also wishes that K should die. All those times, she's regretted her words instantly.
- Ordinary Highschool Student: A normal highschool student, but while working for K, she's met a lot of weird creatures and circumstances.
- Pint-Sized Powerhouse: A regularly tall highschool student, but she's strong enough to lift a huge boulder blocking a door.
- Stepford Smiler: Jin certainly shows being happy a lot, but she's still hurt by the loss of her family.
- Unlucky Childhood Friend: She's been friends with Byeong-Hui for years and has had a crush on him for that long, too. She never admitted anything, because she was scared he'd date her, simply to not hurt her feelings. When she eventually does confess to him, he rejects her and Jin decides to not see him for a while.
A wizard who fulfills a person's wish, but obtains their most treasured possession in return. He's been around for ages and was taught how to be more human under his master's training, while also being made a wish-fulfilling wizard. K belongs to a race of people, who assimilate themselves to their loved one and will die of a broken heart, when their beloved dies.
- Crazy Jealous Guy: K is a horribly jealous guy when in love. His beloved is his possession and you do not touch it!
- Defrosting Ice King: He warms up to Lyu-Jin, as time goes by. Taken rather literal, since his hands are icy-cold by nature, but they become warm.
- The First Cut Is the Deepest: The first time he fell in love was with his master, but because he was forced into removing his love through magic, he didn't love him anymore, but all sorts of regret and pain is still inside of him. And K says that this is why he has such difficulty learning about love.
- Good Smoking, Evil Smoking: He takes up smoking partway through the story, then stops. Then starts again, during the final few chapters. K started smoking after Jay died, likely a form of grieving. He stops as he warms up to Jin, but starts again when Seven takes his love away.
- Heroic Sacrifice: K tries to pull this in Happy Birthday, when he says that he'll resurrect Jin's family as a birthday gift. He knows that this will kill him, as it's beyond his capabilities, but he wants to make Jin happy and atone for his sins. It ultimately doesn't work, because Jin figures it out.
- Jerk with a Heart of Gold: He's actually a good guy, deep down. K doesn't take wishes stated by his friends, because he doesn't want to take their most treasured thing from them, he never meets Jay, unless it's either of their birthdays, since he knows that Jay dies when he's too happy. And if someone's treasure possession is something really valuable, he won't take it. Which makes his uncaring attitude, when a client's 'payment' is her father, all the more shocking.
- Look-Alike Lovers: An attribute of his race, they assimilate to their loved on. They begin to feel the same as their loved one, meaning they feel sad when the other is, but will also die when the other dies, and begin to imitate their style of clothing and hairdo.
- My Greatest Failure: K hates himself, because he couldn't save the master thousands of years ago. He also blames himself for causing the death of an actress and a (corrupt) politician, because her wish involved something he was against doing, and she killed the politician and then herself.
- #1 Dime: The treasured possessions from his clients. Ancient, expensive vases or paintings, pointless things like a piggy-bank filled with a little amount of money, emotions like greed or narcissism, it could be anything. K does admit that he has a little preference for collecting pretty people.
- What Is This Thing You Call "Love"?: The master taught him a lot of things, but never what love was. His master tells him, though, that he'll gradually learn it, as he takes care of Lyu-Jin.
The master Lyu-Ui
Lyu-Jin's older brother and actually the master of K and seven other pupils, which he taught millenia ago. He's a very handsome man, he knows it and is rather conceited about his looks, to the point of annoying arrogance. Lyu-Ui had a cold, shortly before his family was supposed to fly off to Hawaii, but he infected his sister to get healthy and went in her stead.
- Ain't Too Proud to Beg: When K falls in love with him and Lyu-Ui knows he's going to die soon, he begs Seven to save K, by removing his love.
- The Casanova: In several of his lives, including his latest. He even says that he's so popular, because he used to be an Arabian prince. Given his reincarnations, he's probably telling the truth.
- Lady Killer In Love: It's implied that, while he was dating the 'Ice Queen', he didn't see any other girls or even flirted with them.
- Chick Magnet: Tons of female fans in whatever school he was in, but never dated one, except for the 'Ice Queen'.
- Cruel and Unusual Death: Several of his deaths, because of the curse Seven placed on him. He's been beheaded when he was royalty, has died of disease, been eviscareted mid-air from an airplane explosion and was once the victim of a serial killer, who chopped him up into several pieces.
- The Gadfly: K sees him like this repeatedly and Lyu-Jin also remembers her brother like this. Lyu-Ui even appears as an actual fly (which turns out to actually be a wasp) to talk to K at one point, bugging him like crazy.
- Go Out with a Smile: In the flashback chapter dealing with his latest death, Lyu-Ui is sad on his last day, because dying is always painful and sad. But when his then-girlfriend, K and even Lyu-Jin all give him smiles in their ways and say goodbye, he's seen smiling himself before the explosion.
- Proud Beauty: Lyu-Ui is well aware that he's very handsome. He sometimes even jokingly says that it's a curse.
- Really 700 Years Old: His exact age is never stated, but it's implied that he's ancient and was actually a deity, who came down to earth.
- Reincarnation: Due to the curse placed upon him, Lyu-Ui keeps getting reborn.
- The Reveal: It's made obvious to the reader very early on, that Lyu-Ui and K's Master are the same person. Lyu-Jin doesn't learn this until very late into the story.
- Sink-or-Swim Mentor: He's a pretty brutal master. When he taught K what 'getting a shock' meant, he brought him to a lake, asked if he could swim and, when told he couldn't, shoved K in and almost let him drown.
Jay & Yuri
An old friend of K's and one of Lyu-Ui's pupils. Jay belongs to a race of people who die when they become too happy and he was taught by Lyu-Ui to learn to control his emotions of happiness, so that he wouldn't suffer by being complimented or similar. He has a student himself, Yuri, who is the same race as K and he's been teaching her human emotions for 100 years.
- Cannot Tell a Lie: Jay sucks at lying. The only reason why his lie to Yuri (initially) worked, was because she had never been lied to before and didn't know that it actually existed.
- Foil: To K. Jay is a friendly, open and overall very emotional person, contrasting K, who belongs to a race that has no emotions to begin with and needs them to be taught to him.
- Go Out with a Smile: A trait of his race. When they become too happy, they die. K actually mentions that this means Jay will die with a smile on his lips, indicating that it's actually a good thing.
- Nice Guy: As a complete contrast to K, he's a very nice guy and very friendly.
- Together in Death: Jay knows he'll die soon, but is horrified that Yuri will follow him, because she loves him. But this is ultimately their fate, Jay dies happily and Yuri follows him a week later, because her heart finally broke.
- What Is This Feeling?: Since Yuri needs to be taught emotions, she can't express them well and tries to describe them. When Yuri explains her feelings for Jay, she says it's love. Shocked, Jay tells her that she's just suffering from constipation.
Another student of Lyu-Ui's. She's a well-meaning witch and always happy to use her magic to solve problems, but she's not very good and often messes up. Dee undergoes severe training several times, just in order to improve herself. But because of her reckless useage of her magic, she often ends up causing more harm than help.
- Break the Haughty: Her introductiory arc revolves around knocking some sense into Dee, to stop her from using her magic so freely, since it has backfired horribly.
- Cannot Spit It Out: Has a horrible case of this towards Wye, so she decides to fight with him a lot.
- Cloudcuckoolander: When it comes to magic and what exactly the problem with certain things are. She locks K into a tree-prison, throws the key away and tries to teleport him out of it. The spell fails and Dee decides to not look for the key and open up, but instead leaves to figure out the problem and then improves her skills for years on end.
- Heavy Sleeper: She falls asleep as soon as the sun sets and won't wake up before it's light again. This is why she never saw Wye without his bandages and is convinced he's an old man.
- Rich Bitch: Used her magic to obtain riches and a castle and comes across as pretty mean towards Lyu-Jin, when they first meet.
- Tsundere: Type A towards Wye, until things settle down. Then she's just openly sweet towards him.
- Well-Intentioned Extremist: Dee certainly means well, but her actions and ways of doing things are just a little to out there. Since she knows Jay will die if he becomes too happy, she create a potion medicine for him that will make him super unhappy. And because she wants K to experience the wonderful warm feelings of love, she spikes his drink with a love potion. Twice.
An old wizard who became arrogant because of his skills. Eventually, he was arrogant enough to resurrect dead people and was adored, but also feared. Wye created a love potion that made men and women fall in love with him, but when his obsessive fans began to rage war amongst themselves, he ran off into the desert to die. Unfortunately, the sun began to fall in love with him and Lyu-Ui took him in as another pupil, including giving him a way to hide himself away from the sun.
- Bandaged Face: Wye has bandaged his face and keeps everything about his body covered up, to avoid the sun. Ditches them when, after his resurrection, the love potion on him stopped working and he can freely walk around.
- Bishōnen: Quite handsome under those huge sunglasses and bandaged face.
- Brought Down to Normal: His wish to K does this to him. Wye wishes to give all his magical powers to Dee, with a plan behind it that would cause Dee to learn to take some responsibility for her actions.
- Cool Old Guy: He certainly looks young, but his voice is stated to sound like an old man's and he talks like an old man.
- Death Seeker: Was one millenia ago, when he was sick of humanity for adoring, but also hating and relying on him for magic and went into the desert to die. Lyu-Ui stopped him, though, and said that he'd make sure to show Wye something that 'would make him feel bad, if the world were to end'.
- Heroic Sacrifice: Throws himself in front of Dee, when her love-potion-obsessed stalkers are about to cleave her in half. Since Dee got all of his magical powers, including a spell that can resurrect people, Wye comes back to life. And he apparently planned the entire thing up to that part.
- Manipulative Bastard: Wye knows that Dee's carefree attitude about her magic might end up as badly as it did for him, so he concocts a plan to allow Dee to mess up as badly as she can, before doing something that would shake her entire world view and get her to realize that using magic willy-nilly is not good.
- So Beautiful, It's a Curse: More like a love potion and he brought it on himself. Unfortunately, the potion was so strong, that even the sun itself began to fall in love with him and was going to descend onto earth, just to be near him.
The last of Lyu-Ui's pupils, he's a mutant of K's race and seems to have a pretty good grasp on emotions to begin with. Seven caused some major ruckus among the group millenia ago, especially between himself, K and the master. He's the one who sets up the main conflict in the final volume.
- Belated Love Epiphany: When Lyu-Ui initially dies, Seven promised to laugh out loud, but ultimately couldn't, because he then realized that his heart was breaking.
- Disproportionate Retribution: Seven was already angry with K for not helping him save Lyu-Ui millenia ago, but when K arrived late to Lyu-Ui's funeral in the 18th Century, Seven decided to torture K, by causing harm to his beloved and ultimately kill K, too.
- Dude Looks Like a Lady: He's got very fine facial features and long hair, causing initial confusion on Jeong-Hwa's side on whether he's a man or a woman. Lyu-Jin figured him out pretty fast, then used her hand to pat his chest.
- Mutant: Of K's race, meaning that he won't assimilate himself to his beloved, if he happens to fall in love, and that he can come back to life, because his heart can regenerate itself after breaking.
- Never Got to Say Goodbye: There was no real goodbye when Lyu-Ui first died. And despite Seven trying to find him, to remove the curse he placed on Lyu-Ui, he never manages to find him in time, only getting there after Lyu-Ui has already died.
- Reality Warper: His powers include being able to tell what a person is the most afraid of and causing it to become a reality. They were initially sealed, when he became Lyu-Ui's student, though.