Yumi's Cells

After the breakup with Ba-bi, Yu-mi's writing improves greatly thanks to Writer Cell who has become the Prime cell. Now a successful entrepreneur, Woong is surprised to find that Yu-mi is now a writer. When he meets Control Z through a business meeting and learns that he is the illustrator for Yu-mi's works, his heart pounds restlessly...

Yu-mi starts working with the oddball illustrator Control Z. Although she's on the verge of exploding when Control Z nitpicks at everything, she controls herself to stay professional. When Yu-mi flies to Jeju to spend the new year with Ba-bi, she finds out that Ba-bi is giving up his lease.

Da-eun, an intern at Daehan Noodles' Jeju branch, likes Ba-bi but she decides to give up when she realizes Ba-bi has Yu-mi. Meanwhile, the chief editor at Julie Literature, Ahn Dae-yong, finds out that Yumi, the writer he picked, is his first love from his college days and believes that this is fate...

Unlike her courageous start, Yu-mi continues to taste failure from all her contests. Despite Writer Cell's efforts to keep her mind together by recalling wise sayings, Yu-mi feels dejected at her own lack of talent... At that moment, she receives an offer from Mr. Nam to reinstate her position at Daehan Noodles.

Yu-mi works hard from day-to-day as an aspiring writer. Ba-bi visits her house to cheer her on. While the two of them are enjoying their date, an unexpected visit from Yu-mi's parents catches them by surprise... Yu-mi's father begins to openly keep Ba-bi in check.

Yu-mi and Woong meet again during second-hand market meet up. Unlike Woong who thought it was a fateful meeting, Yu-mi is confused by what Woong said in the past as compared to his current situation. While Yu-mi is trying to enjoy her Christmas with Ba-bi, a message from Woong arrives.

Yu-mi's sweet romance with Ba-bi begins... Her new romance leads her onto a new path. When Yu-mi goes to a book cafe with Ba-bi, she is reminded of her long-lost dream. Although she knows it's too late, someone keeps encouraging Yu-mi to pursue her dream.

News of Ba-bi's date puts Yu-mi in despair. Yu-mi wishes he doesn't go on the date. But she couldn't tell him in the end... On the day of Ba-bi's date, Yu-mi falls asleep after feeling perturbed the entire day, when a message from Ba-bi arrives.

Although Yu-mi was taken aback by Ba-bi's sudden confession, her confidence level shoots up. Yu-mi becomes more preoccupied by Ba-bi and she unconsciously finds herself getting heated up when Ruby sets up a date for Ba-bi.

After breaking up with Woong, Yumi and her cells are struggling to keep her life together. Although she acts as if nothing happened, Yu-mi is suffering from post-breakup syndrome and Ba-bi comforts her. In no time, a Yoo Ba-bi club has formed in the cell village without Yu-mi realizing...

Yumi's Love cell is good at everything, but she has one weakness. Thus, the cells suggest that Ruby becomes her private tutor to help Love Cell! Meanwhile, Ba-bi who has been paying attention to Yumi's social media posts, gives Yumi an unexpected suggestion, making her heart race.

Yumi finally explodes in anger when Sae-yi moves houses. The breakup alarm gets activated in Yumi's cell village. They risk breaking up if Woong doesn't contact her in 24 hours. While the couple goes through a cold war, Sae-yi takes this opportunity to get between them.

Rumors about Yumi and Woong's wedding spread like wildfire. However, the two of them have different thoughts about marriage. Meanwhile, someone unexpected appears in front of Yumi as she prepares for a marathon. Who is this guy who found her missing umbrella...?

At a friend's wedding announcement, Yumi mentions that she has a boyfriend. When her friends don't believe her, she proclaims that she will bring Woong to the wedding. But Woong is too busy, she has no choice but to... Just as she was about to give up, another situation crops up where it becomes necessary that Woong attends the wedding.

Having only dreamt of it, Woong finally visits Yumi's house. That night, Yumi and Woong spent an unimaginable night together. At Woong's suggestion, the two of them decide to go on a trip. Yumi's heart races at the thought of a hotel stay with an ocean view, even though her Travel cell is dead. Also Naughty Cell's heart is racing, too...

Sae-yi, the friend that Woong often mentioned, turned out to be a woman! "Can men and women be platonic friends?" The cells break into a heated discussion. On Yumi's birthday, Yumi visits Woong's game studio and finally comes face-to-face with Sae-yi at an unexpected place.

Woong ran in the rain to bring Yumi to the hospital. Finally, the door to Yumi's heart that was shut tightly opens up again... Meanwhile, Woong's female friend Sae-yi starts developing weird feelings when Woong starts dating.

Although his first impression was a total bust, Gu Woong turns out to be more decent than Yumi thought. Yumi's heart seemed to be opening up to the easygoing and honest Woong... But why doesn't he reply? Yumi's mind is coming to all sorts of weird conclusions to understand why Woong didn't reply!

Yumi gets to go to the flower festival with Woo Gi, alone! However, Ruby keeps following them and disrupts the date of her dreams before it even begins. The ultimate chase between Yumi and Ruby begins. Meanwhile, Woo Gi makes up his mind to ask Yumi the question that has been on his mind.

Cells live inside Yumi's head, a 32 year-old who works at Daehan Noodles' finance department. In her dull life where her main concerns are what to eat or wear, only one thing excites Yumi and her cells — Woo Gi from Sales! He's handsome, gentlemanly, and 5 years younger... Age doesn't matter if he's just a crush, right? Or she thought, but Woo Gi keeps hanging around her. Is this a green light?