Characters from Yumi's Cells. Since this is a completed work with Self-Fulfilling Spoilers, spoilers are off.
open/close all folders
Yumi and her Cells
Yumi Kim
Yumi Kim (김 유 미 Kim Yumi)
Portrayed by: Kim Go-eun
The titular protagonist. She is an assistant manager in the accounting department at Daehan Noodles until she quits her job to become a writer.- Adaptational Dye-Job: She's blonde in the comic but has realistically darker hair in the adaptation.
- Amicable Exes: She and Woong reach a point at which they can congratulate each other on their life achievements. She doesn't get to that point with her other exes.
- Big Eater: Her largest cell, Hunger Cell, has a huge influence on her. Thus she frequently makes decisions based on food and eats massive quantities of it.
- Can't Hold His Liquor: In comparison to other characters, Yumi gets drunk really quickly. Only her Inner Feeling Cell is immune to the effects of alcohol.
- Clingy Jealous Girl: She doesn't like it when her boyfriend looks at other women, to the point that "being attracted to another girl for even a second" is a major turn-off for her.
- Covert Pervert: Despite her meek and shy personality, Yumi has an active Naughty Cell that has to be kept in check by the others.
- Earn Your Happy Ending: It took much pain and effort, but by the series' end, Yumi has a successful career as a writer, marries the man of her dreams, and gains the self-confidence to build healthy relationships with her colleagues, including an unexpected friend like Ruby who hated Yumi's guts in the beginning of the series.
- Emotion Suppression: She keeps her Inner Feeling Cell locked up deep in her mind so that it won't blab about something that could compromise her relationships with others.
- Expository Hairstyle Change: She has been debating whether to grow her hair out, and she finally decides to do after the Cells free Silkie from the Bobites, while she's dating Babi. She cuts her hair during important events like becoming a published author.
- Hopeless Suitor: Towards Wook. They have a few tender moments, but Wook doesn't seem to catch on because he isn't interested in women and Yumi isn't as overtly flirty as Ruby. When Yumi's Inner Feeling Cell asks Wook why he doesn't just ask her out, he seems to be caught off guard.
- Hysterical Woman: One of Yumi's recurring cells is Hysterius, a mischievous boy who wants to make Yumi release all of her pent-up frustration. Hysterius cells also exist in other people, but it's only consistently been Yumi with one to stir up trouble.
- Important Haircut: After Yumi breaks up with Babi, she cuts her hair short so she can focus better on writing in the summer heat. Similarly, she cuts it back to her original style after she releases a novel under Soonrok's management.
- Informed Ability: Yumi is said to be a great writer. While we do learn that she loses a few contests and eventually writes a popular web novel, we don't get many actual looks into her writing style and can only glean from what the others tell the audience.
- Loners Are Freaks: Yumi's still single partly because she avoids social activities such as going out drinking with her coworkers.
- Ma'am Shock: After learning that Soonrok is three years her junior, Yumi ponders whether he only thinks of her as his Nuna rather than as a dating prospect. She is nonetheless shocked when he calls her "Nuna" to break the ice and takes a while to get over that appellation.
- Never My Fault: Yumi's Judge Cell embodies this part of her personality, constantly insisting that other people are at fault whenever she suffers from relationship problems.
- Oblivious to Love: Yumi is the subject of at last three unnoticed crushes: a boy she knew in college (who grows up to be her chief editor), with her boss at the office, and with Babi.
- Older Than They Look: She looks quite young both before and after the webcomic's Art Evolution. She is 31 years old in the beginning and is in mid-thirties by the end of the series. Despite this, she looks no older than her younger acquaintances like Ruby.
- Properly Paranoid: She was right to be concerned in the two times another girl caused a strain on her relationship. Sia's mixed signals were actually an attempt to drive apart Yumi and Woong, and Babi was getting swayed by a mutual crush on his part-timer Da-eun.
- Pursue the Dream Job: After rediscovering her potential as a writer, Yumi quits her office job and becomes a freelance writer. She starts out by entering contests and holds a part-time job to pay the bills. Once Daeyong comes across one of Yumi's manuscripts, he helps her publish it, giving her the big break she was waiting for.
- Shrinking Violet: Yumi struggles to speak her mind and stand up for herself. After she starts going out with Woong, she does become more confident eventually.
- Significant Wardrobe Shift: Yumi's Fashion Cell is freed from prison when Yumi tries to win over Wook and starts putting more effort into her appearance. After Yumi's first break-up with Babi, Fashion Cell morphs into a Fashion Terrorist and makes Yumi dress very casually and comfortably.
- Super Mode: In Chapter 121, she enters "Ultra-Yumi Mode" when her self-esteem levels go up over 3,000.
- Too Unhappy to Be Hungry: When Yumi feels guilty about reciprocating Babi's feelings while Eda has a crush on him, she can't bring herself to eat all the food she loves, which causes her to get indigestion.
- Trademark Favorite Food: Yumi's favorite food is tteokbokki, which is her profile picture and the food on Hunger Cell's antenna.
- Waiting for a Break: When Yumi quits her office job to pursue writing, she takes up a part-time job at Sundol Books to make ends meet. When the bookstore closes down, she goes back to the office to fill in for Eda. At the same time Yumi finds out she can't get her full-time position back, Daeyong comes across one of her manuscripts and gives her a big break, ensuring she never has to worry about money again.
- Weight Woe: Yumi is conscious about the Fat that lives in her sides, but her Diet Cell has a soft spot for Hunger Cell and doesn't do anything about her food intake.
Rational Cell (Reason)
Rational Cell / Reason
Voiced by: Shim Kyu-hyuk
The embodiment of Yumi's logic.- BFG: He often uses a bazooka to blast illogical Cells out of the way. It can hit Cells from an impressive range so they won't know they're being targeted, but it can't help when he gets dogpiled.
- Butt-Monkey: Frequently gets beaten up when he tries to get the cells to think logically. On the extreme end, he winds up in a different dimension long enough for Yumi to get back together with Babi.
- Only Sane Man: Often the sole voice of reason when Yumi is overcome with feelings, which doesn't end well for him when dozens of other Cells disagree with him and stampede all over him.
- Vitriolic Best Buds: He's bunkmates with Emotional Cell, and they argue the most out of any pair of Cells because they're Emotions vs. Stoicism personified. Their backstory indicates they were practically made to get in each other's way, as Rational Cell was told that it's his job to stop Emotional Cell.
Emotional Cell (Sensitivity)
Emotional Cell / Sensitivity
Voiced by: Park Ji-yoon
The cell that embodies Yumi's emotions, not including love.- Batter Up!: She has a collection of bats, which she frequently wields to attack other Cells who either provoke her or don't do things her way.
- Girlish Pigtails: She has two long pigtails poking out of her suit, evoking the image of a sensitive little girl.
- Prone to Tears: She cries over things that are even just a bit sad, starting as early as the prologue. She can also make Yumi cry by "bursting", something that Rational Cell was made to stop her from doing.
- Vitriolic Best Buds: She and Rational Cell are bunkmates and the duo that argues the most, embodying the conflict of Emotions vs. Stoicism. She frequently hits him over the head to get her way, though the reverse sometimes happens.
Naughty Cell
Naughty Cell
Voiced by: Ahn Young-mi
The Cell that's responsible for Yumi's dirty thoughts.- Lovable Sex Maniac: He runs wild with the naughty thoughts and has to be kept in check by other Cells, hence Yumi's covert pervertedness. However, his actions are usually comedic and occasionally useful in Yumi's romantic endeavors.
- Naked People Are Funny: As a probationary Cell, he actually never wore pants. All his front-facing panels were censored in various comedic ways.
- Naughty by Night: The most he can do in polite company is cause Yumi to blush by setting the village on fire. When Yumi is alone with her significant other, however, he takes control of Yumi and unleashes all the flirty maneuvers.
- No Sense of Personal Space: When Soonrok's Love Cell walks near him, he goes straight for The Glomp, embarrassing everyone in the town. This corresponds to an Accidental Hand-Hold.
- Pyromaniac: He loves to set Yumi's village on fire when she's near someone she likes, sometimes as an act of revenge against the other Cells who tried to repress his actions/Yumi's dirty thoughts.
- Series Mascot: So popular he actually became Webtoon's mascot while the comic was running, often used to advertise their merchandise page.
- Sir Swears-a-Lot: He has the most censored lines out of all of the cast, mostly to do with naughty acts.
Hunger Cell
Hunger Cell
Voiced by: Lee Jang-won
The largest cell in Yumi's village.- Big Eater: His defining characteristic. When the Cells need to ration their food, he takes the largest portion. When everyone's fighting over what Yumi should do, he can just push them out of the way and steer Yumi towards food.
- The Big Guy: As the largest Cell in Yumi's village, he can brute force decisions that other Cells struggle to make.
- De-power: In Chapter 51, he loses his will to eat when his appetite antenna is torn out.
- Expressive Accessory: The antenna on his head normally has a tteokbokki on it, but it changes to another food when he's craving it.
- Eyes Always Shut: His eyes are closed by default, but he opens them when he's shocked or when he's doing something special like helping out Soonrok's Hungry Cell.
- Manchild: He's a giant building-sized child that is constantly snacking. The others try to keep him under control so Yumi doesn't overeat, but he can get very cranky.
Love Cell
Love Cell
Voiced by: Ahn Soi
Yumi's Prime Cell.- Badass Cape: As the most powerful Cell, she wears a pink one to distinguish her from the other Cells.
- Became Their Own Antithesis: When Yumi attempts to break up with Babi, his words sway Love Cell into giving him another chance. This makes Yumi so upset with her own (and Love Cell's) indecisiveness that she turns Love Cell into Anger Incarnate, which makes it impossible to date Babi anymore.
- Brought Down to Normal: After being demoted from Prime Cell, she's unable to use her skills. She's even wearing the regular blue suit during this time.
- Earned Stripes: She has a distinctive pink outfit that marks her as a Prime Cell with special abilities. She loses it when she is demoted.
- The First Cut Is the Deepest: Starts out in a coma, barring Yumi from entering any relationships, because Yumi's last relationship was abusive.
- The Power of Love: Love Cell is so powerful that she can check the Cells that cause harm to Yumi, including Hunger Cell, the source of Yumi's untameable appetite.
Fashion Cell
Fashion Cell
Voiced by: Kim Yeonwoo
The Cell that's responsible for dressing Yumi well. She was in prison for wasting a huge chunk of Yumi's budget, but she gets parole when Yumi needs to dress to impress her crush.- Arch-Enemy: She has the most conflicts with Cheapskate Cell, who never lets her buy what she wants, even when he starts spending willy-nilly as Giving Tree.
- Became Their Own Antithesis: As Yumi breaks up with Babi, Fashion Cell turns into Fashion Terrorist and starts to be lazy in picking Yumi's clothes.
- Dressing Down: After Yumi breaks up with Babi, Fashion Cell turns into Fashion Terrorist and becomes lazy with the clothes-picking.
- The Fashionista: She's responsible for dressing Yumi well but tends to go above the budget.
- Foil: To Cheapskate Cell. They both love money, but Fashion Cell likes buying nice things with it while Cheapskate Cell would rather save it. They both undergo a personality flip that makes them indifferent for money. Fashion Terrorist uses frumpy clothes that are not indicative of Yumi's wealth, while Giving Tree spends it freely.
- Ms. Red Ink: She tends to be responsible for running Yumi's budget into the ground by buying lots of clothes.
- Significant Wardrobe Shift: Any changes to Yumi's style are associated with her. While she's in prison, Yumi doesn't care about her looks. After she gets paroled, Yumi starts putting effort into her look. When she turns into Fashion Terrorist, Yumi takes Dressing Down to a new level.
Cheapskate Cell (Stingy)
Cheapskate Cell (Stingy)
- Arch-Enemy: He mostly butts heads with Fashion Cell, who is most responsible for wasting Yumi's budget.
- Became Their Own Antithesis: He turns into a Giving Tree when Yumi breaks up with Babi and starts spending money like it grows on trees. He still exercises control over Yumi's budget and won't let Fashion Cell buy anything.
- Butt-Monkey: The other Cells trample all over him when he suggests cutting their favorite things out of the budget, and they buy what they want anyway.
- Foil: To Fashion Cell. Cheapskate Cell is stingy with money, but Fashion Cell likes to flaunt what she has. They both turn into their opposites, where Giving Tree spends the money and Fashion Terrorist doesn't bother reflecting Yumi's wealth.
- Gender Flip: Cheapskate was androgynous to begin with but is female in the TV drama.
- The Scrooge: Even as a Giving Tree, he won't just let the other Cells buy things and makes them line up for approval. He eventually reverts back to Cheapskate when Soonrok buys an expensive ice cream sampler.
Kindness
Kindness
- Embodiment of Virtue: Inverted. She represents kindness but is quick to resort to violence.
- Good is Not Nice: Kindness is mean to other Cells if they aren't being nice.
- Good Is Not Soft: She resorts to violence if the other Cells won't let Yumi be kind.
- Good Wings, Evil Wings: She has white angel wings and represents kindness.
- Ironic Name: For a Cell named Kindness, she isn't very kind to the other Cells.
- Sir Swears-a-Lot: She swears enough for the other Cells to wonder if she is actually a Swearing Cell.
Writer Cell
Writer Cell
- Artsy Beret: He sports a beret as a quick indicator that he's the creative Cell.
- Back from the Dead: He rises from the grave and uses his Scenario skill to get Yumi to go to Woong after they fight.
- Badass Cape: Once he is promoted to Prime Cell, he gets a cape to complement his new powers.
- Can't Take Criticism: When told that his story lacks tension, he says he would rather go back to his grave than change the story. However, he changes his tune after Cheapskate Cell spends a day digging his grave.
- Earned Stripes: When he becomes Prime Cell, he gains a green Shakespearian outfit to mark his promotion.
- Gender Flip: Writer Cell is female in the TV drama, but it doesn't have much of an impact on the plot due to the gender-neutral Korean personal pronouns and lack of Tertiary Sexual Characteristics.
- Hat of Authority: Upon his promotion to Prime Cell, he trades his Artsy Beret for a tall green feathered hat. If the distinct color didn't already indicate his leadership, the distinctive hat would.
- Married to the Job: After he becomes the Prime Cell and Yumi leaves Babi for good, he refuses to let Yumi enter another relationship and arrests Cells that are looking for love.
- Posthumous Character: He's dead at the beginning of the story due to disuse.
- Regal Ruff: As a Prime Cell, his outfit includes a ruff as part of the Shakespearian theme.
Yumi's Love Interests
Wook Chae (Chae Wu Gi)
Wook Chae (채 우 기 Chae Wu Gi)
Portrayed by: Choi Min-ho
Yumi's first crush in the office. He works in the sales department at Daehan Noodles.- Age Lift: In the drama, he's stated to be five years younger than Yumi, whereas he is six years younger in the webtoon.
- Barely-Changed Dub Name: His Korean name is U-gi, which could be spelled "Woogie". "Wook" sounds similar but would be written differently in Hangul.
- But Not Too Gay: While he comes out to Yumi very early into the series and has his own love interest, Wook is usually playing off of Woong (his buddy) or Ruby (his most persistent admirer). His love interest is unnamed and doesn't show up until Chapter 504 for a single panel.
- Closet Gay: He tells Yumi that the person he's interested in isn't a girl but also says it's a secret. When the guy finally shows up, Wook refers to him as his friend ("...that I told you about before") so only those privy to his orientation would catch on.
- Expository Hairstyle Change: When he's introduced, he has short bangs and looks friendly and approachable to Yumi. After a time skip, his bangs are long enough to go over his left eye, giving him more mystique and making him look colder. It coincides with Ruby finally realizing he will never be interested in her and getting over him.
- Incompatible Orientation: Neither Yumi nor Ruby has a chance with him because he is interested in a guy.
- No Full Name Given: In the English translation of the comic, Wook's family name is never revealed. However, it is revealed right away in the drama as well as in the Korean-only follow-up comic.
- Only Sane Man: He's definitely the most sensible and down-to-earth person in the comic. He sees Sia for what she is and intervenes to check her behavior, and often is the only one who sees the simple and obvious option other characters are missing.
- Significant Name Overlap: He has the same name as Yumi's ex-boyfriend, and it's likely the reason she fixates on him at first—even internally regarding him as her "destiny" until she decides to give Woong a chance.
- Straight Gay: He's an ordinary office worker who gives sensible advice to Woong and tries to gently let down suitors who aren't interested in him. If he hadn't admitted to Yumi that he's not into girls, it wouldn't be obvious that he is gay. In fact, Ruby might not have figured it out since she kept chasing him for three years.
Woong Ku (Gu Wung)
Woong Ku (구 웅 Gu Wung)
Portrayed by: Ahn Bo-hyun
Wook's friend and Yumi's blind date. He works at a gaming company and eventually becomes a successful CEO.- Attention Deficit... Ooh, Shiny!: Woong's Prime Cell is Concentration Cell, but he's always asleep and has to be awakened by a specific ritual that will fail if any distractions come into play. However, his focus is unbreakable once he's awake, and the ritual can be bypassed if Woong is sufficiently invested in the subject.
- Expository Hairstyle Change: He gets a haircut when he's in need of a job to symbolize him letting go of his pride. A few years later, he has become successful and let his hair grow even longer than before.
- False Soulmate: Yumi believes he's her destiny and has to be told by the bulletin board manager that there is no male main character in her life.
- He Cleans Up Nicely: He has a bizarre sense of fashion and doesn't put much effort into his appearance, but he shows up to a party looking decent when Yumi expected him to look like a beggar.
- Important Haircut: Woong cuts his hair for a job interview, which represents how he's swallowing his pride so he can make a living.
- Impossibly Tacky Clothes: Once he becomes successful, he starts wearing clothes that are eye-catching for the wrong reasons. Between the brightly-patterned tops and unprofessionally short shorts, it's no wonder Wook told him not to go outside looking like that.
- Manchild: Yumi's Cells describe him specifically as a "sloppy, self-centered person with a boyish heart".
- Oblivious to Love: Woong didn't know how Sia felt about him for the longest time, since she constantly hid her feelings around him and when she actually flirted he didn't know what she was going for.
- Pride: Pride Cell gets in the way of healthy communication between Woong and Yumi. Woong can't admit his poor financial state to Yumi or else Pride will blow up his village with explosives. A while after the break-up, Rational Cell ditches Pride in the middle of nowhere so Woong can be happy. In the adaptation, Pride is also the Prime Cell after Gamer Cell splits.
- Pungeon Master: More pronounced in the Korean version, but he loves using word play as part of his jokes.
- Punny Name: His given name is a casual way of saying "yes". Yumi weaponizes this to make him deliver a Blunt "Yes" to Sia.
- Rags to Riches: He dates Yumi when his company is going under, but he becomes very successful years after the breakup.
- Royal Brat: Chapter 58 introduces Woong's King Pouty, in which it takes him three years to leave once he settles somewhere.
- Second Love: After Yumi went through a break-up and became emotionally withdrawn, she was able to open her heart to Woong.
- Unable to Support a Wife: When Yumi brings up the topic of marriage, Woong hesitates to respond because he's afraid of what would happen if he went bankrupt and couldn't support her.
- Unconfessed Unemployment: Woong sells his apartment and lives in his studio due to financial troubles and doesn't tell Yumi until she finds out. When they break up, he tells her that he got a good contract when his studio is actually going under.
- Wardrobe Flaw of Characterization: Once he returns to the limelight after becoming successful, he looks more polished and professional. Then he stands up, revealing that he's wearing short shorts. This indicates that despite his success, he's still a sloppy manchild at heart.
Babi Yoo (Yu Babi)
Babi Yoo (유 바 비 Yu Babi)
Portrayed by: Park Jin-young
A guy who works in the marketing department at Daehan Noodles. He and Yumi first meet when he finds and returns her lost umbrella.- Chick Magnet: He has attracted many women over the course of the series, including Eda, Yumi, Yunhee, and Da-eun. Yumi kept her guard up while she and Babi were both in separate relationships, but she fell for him after they both became single.
- Crazy Jealous Guy: Though he gives Yumi his infinite trust when she meets her ex-boyfriend Woong early in the relationship, he admits that he gets jealous a lot. That infinite trust card is a ploy to make Woong unable to sway Yumi. Babi also goes out of his way to stop Yumi from eating the donuts Daeyong gave her. After a short breakup period, Babi's Jealousy Incarnate flares up when Yumi takes Woong to the hospital, prompting him to go to them.
- Dreadful Musician: His Singing Cell's trait is "terrible singer". It got locked up after embarrassing him at karaoke one night.
- Emotion Suppression: His Overreacting Cell tends to make him too kind in situations that could be terribly misinterpreted. Thus he keeps it locked up, forcing himself not to overstep his bounds.
- Oblivious to Love: When Babi was in high school, he lent his scarf to a senior, causing her to fall for him. When she called on him to personally say goodbye before graduating, he was oblivious until she told her not to send such a confusing signal. Later on, Babi is completely unaware of Eda's crush on him.
- Pursue the Dream Job: After his father retires, Babi rediscovers his passion for cooking, quits his office job, and opens up a tteokbokki place. It leaves him with less free time, but he genuinely enjoys it.
- Wolf in Sheep's Clothing: The Cell that was once thought to be Babi's Kind-Hearted Cell has wolf ears and is clad in fleece. It turns out to be an Overreacting Cell whose unnecessary kindness to girls he isn't dating tends to get him into relationship troubles.
Soonrok Shin (Sin Sun Rok)
Soonrok Shin / (신 순 록 Sin Sun Rok)
- Clark Kent Outfit: Between his crisp suits and loose casual clothes, he doesn't show much muscle. It's revealed that he's very well-built when he catches Yumi in the middle of a Staircase Tumble.
- Covert Pervert: He comes off as either cold or innocently affectionate, but he implies that he wants to get right into hand-holding, hugging, and cheek-kissing when he starts dating Yumi. This causes Yumi's Cells to complain that her Naughty Cell is too old. It turns out Soonrok's Naughty Cell is larger than he is and as muscular as Daeyong's cells.
- Cute Bookworm: When he's at home and able to enjoy his books in comfort, his eyes become round and his hair returns to its natural curly shape. He and Yumi acknowledge how cute he is in this state.
- Glasses Are Sexy: The glasses, in combination with the suit and cold personality, make him very attractive in Soohyun's eyes.
- The Glasses Gotta Go: Downplayed; he's attractive with or without the glasses, but Yumi remarks that he's really cute without them.
- Hates Small Talk: As a textbook introvert, his energy drains in social interactions so he takes the route of least conversation whenever small talk is involved.
- Last Episode, New Character: In the TV drama, he is introduced at the end of the last episode of Season 2. Yumi met him at the corporate party but was too drunk to remember him, so she gets his name through text.
- Last Guy Wins: He's the last of Yumi's love interests to be introduced — appearing only in the last 70 episodes of the 511-episode series — and is the one she eventually marries.
- Mr. Imagination: He loves coming up with imaginary scenarios in his alone time and can fully immerse himself in the settings.
- Naughty by Night: Outside his house, he operates purely on rational thought to preserve his energy. He has a set of rules that he loves to break when he's at home, including neatly taking his suit off and not eating snacks before dinner. Similarly, his gigantic Naughty Cell is a gentleman who only shows up when things are getting intimate.
- Non-Standard Character Design: His Naughty Cell and Tongue Cell are large and muscular, compared to his other Cells which are just like everyone else's.
- Sharp-Dressed Man: He wears crisp suits in the workplace, which contributes to his cold, professional image.
- Strictly Professional Relationship: He has a strict rule of not dating coworkers and draws a line when he catches onto Yumi's hints. He also likes to break his own rules and confesses his feelings to Yumi as soon as he has his Love Epiphany.
- Sugar-and-Ice Personality: He operates on "low power mode" at work to save his energy. He only uses his Rational Cell to get through the day, which makes him come across as quiet and emotionless. In his comfort zone, he is a lot more empathetic and affectionate.
- Third-Option Love Interest: Woong proved to be too immature for Yumi, and Babi was apparently such a perfect boyfriend that the fiasco with his part-timer shattered Yumi's perception of him. Soonrok balances out their good traits: He's mature and professional but has a cute and fun side, and he's much better at communicating than the other two were.
- Too Much Alike: His blind date with Soohyun doesn't work out because she's so much like him that he has nothing to ask her.
Other Characters
Ruby Lee
Ruby Lee (이 루 비 Lee Ruby)
Portrayed by: Lee Yu-bi
Yumi's rival for Wook. They become more amicable after Yumi gets a boyfriend, eventually becoming close friends.- Aerith and Bob: Downplayed; "Ruby" is actually a common Korean given name, but her name stands out because she's the only main character whose name is explicitly spelled out in natural English, rather than being transliterated from its Korean name. Adding to this, her surname was also never revealed in the webcomic.
- Age Lift: In the drama, she's one year younger than Wook rather than two. Combined with Wook's age lift, this puts her at his age in the webtoon.
- Alone Among the Couples: In the "Ruby Signing Off" saga, she tries to go out for dinner with Yunhee and Eda, but they already have plans with their partners. As Ruby waits alone at the bus stop, she scrolls through her phone, which lists Yumi (who is dating Babi), one guy whose profile picture includes his girlfriend, and another guy whose status is "I'm married".
- Brilliant, but Lazy: Her mill is more advanced and potent than that of the other characters, but it doesn't get much use. When she does use it, it's for superficial things like figuring out Yumi's crush.
- Clingy Jealous Girl: She is pretty hostile to anyone who she thinks is eyeing Wook, and even attempts to get in their way. She stops doing this when she gets over him.
- Heel–Face Turn: She was on bad terms with Yumi in the beginning as they both try to win Wook's love. Ruby gets less confrontational after Yumi gave up on him and later walk out of the job to pursue her dream. But it's when she falls in love with Yumi's co-worker that her bitter side mellowed out for good, and she eventually quits Daehan Noodles to work at Yumi's office and becomes her best buddy, even showing up on Yumi's wedding.
- Hopeless Suitor: No matter how much she drives other girls away from Wook, she doesn't stand a chance because he's not interested in girls and already has someone else in mind.
- Named by the Adaptation: The live-action TV series adds her family name, Lee.
- No Full Name Given: Her family name is never brought up in the comic despite her importance as a character. It's brought up in the second season of the TV adaptation, though.
- Oblivious to Hints: Carelessly says things that offend other people. Sia's Cells try to get her to shut up by using a Hint Radar, but it turns all seven of Ruby's radars are coming up with strange analyses that lead her to think that Sia is after Wook and that her Stealth Insult is a compliment.
- Rejection Affection: Ruby continues to pursue Wook for three years even though he's clearly not interested in her.
- Second Love: She gives up on Wook after three years of unsuccessful pursuit of him, and ends up falling in love with Control-Z.
- Third-Person Person: Invoked. She sometimes refers to herself in third person when she wants to flaunt her cute persona. When she tells Control-Z to "Draw Ruby!" he takes her for a bewitcher who's using the dark magic of romance.
- Took a Level in Kindness: She delivers passive aggression to Yumi at first because she's in the way of pursuing Wook. She gets better after Yumi moves on from Wook, but finding a new love interest in "Ruby Signing Off" really brings out the best in her, becoming an all around nice girl.
Eda Kang (Kang Yi Da)
Eda Kang (강 이 다 Kang Yi Da)
Portrayed by: Mi Ram
One of Yumi's oldest friends at Daehan Noodles. She has an unrequited crush on Babi and thus becomes a temporary obstacle when Yumi wants to date him.- Adaptational Dye-Job: Her hair is a light shade of brown in the adaptation.
- Early-Bird Cameo: She's been present as early as Episode 4, long before she had a meaningful role in the story.
- Happily Married: She gets married to the glasses-wearing coworker who seemed to be interested in her. A few hundred episodes later, she still makes references to her marriage.
- Hopeless Suitor: She has an unrequited crush on Babi. When Babi starts making moves on Yumi, it leads to tension in the women's friendship.
- Limited Wardrobe: She always wears the same green dress, which is called out at one point. She only changes clothes when she's important to the plot.
Sia Seo (Seo Sae Yi)
Sia Seo (서 새 이 Seo Sae Yi)
Portrayed by: Park Ji-hyun
Woong's best friend who gets in the way of his relationship with Yumi.- Career vs. Man: The reason she suppresses her emotional side, and avoids pursuing Woong romantically despite being in love with him, is because having a boyfriend would hinder her ambition to be a famous art director.
- Clingy Jealous Girl: She and her cells have been hiding repressed emotions for Woong because of fear that it would get in the way of her job. Once Woong starts dating Yumi, she starts interfering with their relationship.
- Dub Name Change: Her Korean name is Sae-yi, which could be spelled "Sei". This name slips into earlier chapters and is part of her screen name, Cersei.
- Emotion Suppression: Literally has her Emotional Cell locked up and masks her romantic feelings for Woong.
- Married to the Job: As a means of trying to suppress her love for Woong. Her Love Cell, as a result, isn't focused on romantic love at all; it's actually a love of her career, while her Emotional Cell is the more romantic one.
- Master of the Mixed Message: Sia actively hides her feelings for Woong when he gets suspicious of her and tries to flirt with him when his guard is down. Various people point out that Sia doesn't want to commit to Woong but doesn't want him to date anyone else.
- Mistaken for Romance: She mistakes her own feelings for Woong as romantic. At the end of the story, she realizes that her jealousy was actually her fear of losing a long-time friend, and she gladly lets him go with his latest romantic prospect.
Hanbyeol Kang
Hanbyeol Kang (강 한 별 Kang Han Byeol)
Portrayed by: Kwon Seung-woo
One of the workers in the marketing department at Daehan Noodles. He believes he's one of the hottest guys in the office and considers Wook and Babi his rivals.- Adaptational Dye-Job: He has silver hair in the comic but dark auburn hair in the live-action adaptation.
- The Friend Nobody Likes: His coworkers have their ways of tolerating him. Yumi thinks he's nice at first but is quick to realize how weird he is and to deal with him.
- Shipper with an Agenda: He's happy that Babi has a girlfriend and awaits the day they get married. When they break up, Hanbyeol tries to pair up Babi with Yumi, unaware that Yumi is dating Woong.
- Small Name, Big Ego: He claims to be one of the hottest guys, rivaling Wook and Babi, but it's clear that his coworkers think he's a weirdo.
Daeyong Ahn
Daeyong Ahn (안 대 용 Ahn Dae Yong)
Portrayed by: Jeon Seok-ho
The editor-in-chief at Julie's Literacy Agency. He is Yumi's publisher and had a crush on her when they were in college.- Age Lift: He's the same age as Yumi in the webcomic, but he's several years her seonbae in the drama.
- Big Eater: Even moreso than Yumi. He's described as a "hyper-big eater" who can eat at least five plates of tempura at a bar.
- Hopeless Suitor: He tries to win Yumi over after he becomes her publisher, unaware that she already has a boyfriend. He backs off when he finds out and instantly falls in love with Babi's own Hopeless Suitor, Yunhee.
- Non-Standard Character Design: His Cells are realistically proportioned and freakishly muscular.
- Punny Name: When he finds out Yumi already has a boyfriend, his Love Cell tries to initiate Plan B, only for his Rational Cell to remind him that his name is Ahn Daeyong (you must not do it). When Yunhee addresses him formally, he says, "Daeyong (It's okay). Call me Daeyong."
- Sugar-and-Ice Personality: He's naturally a sweet person, but lashing out lost him a relationship. He adopted a cold personality so that he could surprise people with his sweetness.
Yunhee Park
Yunhee Park
- Adapted Out: She's absent in the drama. Eda takes her role as Daeyong's girlfriend, while Ruby takes her age-related contributions.
- Has a Type: People with a Sugar-and-Ice Personality or Tsunderes can get into her heart by freezing the door and shattering it with kindness.
- Hopeless Suitor: Has a crush on Babi that she tries so hard to deny because he has a girlfriend.
- Never Gets Drunk: She has a very high alcohol metabolism that allows her to drink an infinite amount of beer.
Control-Z
Control-Z (컨트롤 Z) / Jiwon Song (송 지 원)
Portrayed by: Pyo Ji-hoon
Yumi's illustrator for her first novel.- Brutal Honesty: His Inner Feeling Cell is his Prime Cell, which means he has no filter. He makes a terrible first impression on Yumi when he criticizes her novel for being unrealistic.
- Deconfirmed Bachelor: He swore off of dating after the loss of his girlfriend, but he falls for Ruby shortly after they meet.
- Hiding Behind Your Bangs: A huge chunk of hair covers his left eye. It gives him a mysterious vibe as his personality traits and backstory are only revealed slowly. It also marks him as solitary since he has sworn off dating for a long time.
- Long-Haired Pretty Boy: He plays up his cuteness for all its worth and has very long hair.
- Never Bareheaded: He started wearing hats with his first girlfriend and hasn't stopped since.
- Only Known by Their Nickname: His real name is revealed in a flashback, but he is only ever referred to as "Control-Z" or "Z" for short.
- Professional Butt-Kisser: His Loyalty Cell says some might call him a brown-noser, but he's an important part of Z's social life. Z uses this loyalty to make a good impression on Woong in his first interview.
- Second Love: He closes himself off to the dating scene after his girlfriend of 10 years dies, but eventually falls in love and gets together with Ruby.
- Undying Loyalty: Though he lacks a Love Cell, he makes up for it with his Loyalty Cell, which helps him keep his relationship afloat for 10 years.
- What Is This Thing You Call "Love"?: He doesn't have a Love Cell. When a girl first confesses her feelings to him, his Naughty Cell tries to kiss her, which weirds her out. After that, he decides that loyalty is similar enough to love and has his Loyalty Cell carry out those duties.
Da-eun Yoo (Yu Da Eun)
Da-eun Yoo (유 다 은 Yu Da Eun)
Portrayed by: Shin Ye-eun
A part-timer who works at Babi's tteokboki restaurant.- Adaptational Job Change: In the TV drama, she is an intern at Daehan Noodles rather than a part-timer because Babi didn't quit his job to open up a tteokbokki restaurant.
- Cute Clumsy Girl: She makes a lot of mistakes while working at Babi's, and frequently gets the wrong order, drops plates, etc.
- Mistaken for Romance: Due to her Smitten Teenage Girl nature, she often sees romantic intentions where there are none. For example, when her male friend gave her and another female friend a candy and an encouraging note, Da-eun becomes convinced that her male friend is in love with her and even gets Babi to help her find hidden "evidence" of his love in his actually innocuous gift.
- Same Surname Means Related: Discussed but ultimately averted. Da-eun shares the same surname with Babi, which assures Yumi that they're related and therefore can't romance each other. However, they aren't actually relatives, and they eventually marry each other.
- Smitten Teenage Girl: Ever since she was in high school, she has had a tendency to fall in love very easily. In her introduction scene alone, she falls in love with about three different guys for just talking to her (and sometimes not even then).
Soohyun Kim
Soohyun Kim
- Bitch in Sheep's Clothing: She looks like a Shrinking Violet at first and makes Soonrok so comfortable that he just isn't attracted to her. However, she didn't give him a chance because he immediately showed his sweet side, only to pine after him once she saw his cold side at work. When she catches him being romantic with Yumi, she tips off his boss that they're dating and steals an idea from Yumi's manuscript.
- Laser-Guided Karma: Her plagiarism of Yumi's novel is quickly caught on since Daeyong gives testimony about showing it to Soohyun before getting published and is reported to writers' association.
- Pen Name: Isabelle. It contributes to her anonymity when Yumi wants to confront her.
- Too Much Alike: She's not attracted to Soonrok because he's too much like her, not the cold Sharp-Dressed Man she was expecting.
- What Happened to the Mouse?: She disappears from the story before the consequences of plagiarizing Yumi's draft are shown. It probably didn't end well for her, considering it took a toll on her Conscience Cell's nervousness.
