Yumi's Cells (Korean: 유미의 세포들) is a 2021 South Korean television series directed by Lee Sang-yeob and starring Kim Go-eun, Ahn Bo-hyun, Park Jin-young, and Kim Jae-won. Based on the eponymous webtoon, it is a cell-based psychological romance that unravels the daily life of an ordinary office worker Yumi through the eyes of the cells in her head.
The first season was released on TVING from September 17, to October 30, 2021, and aired on tvN every Friday and Saturday at 22:50 (KST). The second season was released on TVING from June 10, to July 22, 2022, releasing two episodes every Friday at 16:00 (KST). It was later aired on tvN from November 16, to December 29, 2022, every Wednesday and Thursday at 22:30 (KST). The third season premiered on TVING on April 13, 2026, releasing two episodes every Monday at 18:00 (KST); it also aired on tvN every Monday and Tuesday at 20:50 (KST).
On September 8, 2021, TVING announced that the drama had sold broadcast rights in more than 160 countries around the world, including Europe, North America and Southeast Asia. On September 15, 2022, it was announced that season 2 had been sold to Amazon Prime Video for broadcasting in Japan.
Contents
Synopsis
The drama tells the story of an ordinary office worker from the perspective of the brain cells in her head that control her every thought, feeling and action.
Season 1
Yumi (Kim Go-eun) is an ordinary woman whose Love Cell has fallen into a coma following the shock of a failed relationship. When she meets Goo Woong (Ahn Bo-hyun), a game developer, his simple and honest personality wakes up Yumi's Love Cell.
Season 2
After parting with Goo Woong, Yumi starts a new relationship with her co-worker Babi (Jinyoung). In the meantime, she rekindles her dream of becoming a writer.
Season 3
Yumi, now in her mid-30s, has become a renowned romance novelist, but she feels a sense of emptiness. The arrival of Shin Soon-rok (Kim Jae-won) plunges her life into a new mix of joy and despair.
Cast
Main
Kim Go-eun as Kim Yumi, an ordinary office worker.
Ahn Bo-hyun as Goo Woong, a game developer and Yumi's second boyfriend and Sae-yi's love interest.
Jun Ho-young as teen Goo Woong
Park Jin-young as Yoo Babi, Yumi's co-worker and boyfriend.
Kim Jae-won as Shin Soon-rok, employee of a publishing company in charge of Yumi's works and eventually her husband.
Yumi's cells
Love Cell (voice: Ahn Soi)
Yumi's prime cell that represents the people. It's the driving force behind Yumi's actions. Other cells wear blue, but it wears pink.
Emotional Cell (voice: Park Ji-yoon)
Emotional cell, responsible for emotion. It has a nocturnal temperament, so at night, it flutters blue leaves and gets wet with sensitivity.
Rational Cell (voice: Shim Kyu-hyuk)
The opposite cell responsible for ideal thinking. When working or having an important conversation, this is Yumi's busiest cell from the moment she wakes up to the moment she goes to sleep.
Hungry Cell (voice: Lee Jang-won)
Cell responsible for appetite and cravings. When this cell wakes up, Yumi's appetite explodes.
Naughty Cell (voice: Ahn Young-mi)
Clumsy sexuality cell that promotes racy thoughts. It spits out obscene words from time to time, most of which are muted.
Detective Cell (voice: Jeong Jae-heon)
Detective cell that analyzes and predicts people and situations around it.
Fashion Cell (voice: Kim Yeon-woo)
Hysterious (voice: Um Sang-hyun)
Anxiety Cell (voice: Sa Moon-yeong)
Inner Feeling Cell (voice: Sa Moon-yeong)
Woong's cells
Rational Cell (voice: Um Sang-hyun)
Humor Cell (voice: Jeong Jae-heon)
Babi's cells
Tongue Cells (voice: Kang Yu-mi)
Supporting
Park Ji-hyun as Seo Sae-yi (s. 1), Goo Woong's colleague. She dreams of becoming the best game art director.
Lee Yu-bi as Ruby, Yumi's co-worker who prides herself on mastering various dating techniques.
Joo Jong-hyuk as Louis (s. 1)
A game developer workaholic. Goo Woong, Seo Sae-yi, and he were college classmates, who have set up and run an online game company.
Jeong Soon-won as Chief Nam Joo-hyuk.
Kim Cha-yoon as Lee Bonnie, an employee of Daehan Noodles' marketing department.
Mi-ram as Yida, Yumi's friend and her co-worker at Daehan Noodles.
Jeon Seok-ho as Ahn Dae-young (s. 2–3), editor-in-chief of Julie's Literature History.
Cho Hye-jung as Baek Na-hee (s. 3)
Yumi's assistant writer.
Park Se-in as PD Jang (s. 3), Yumi's PD.
Choi Daniel as Kim Joo-ho (s 3), the lead writer at Julie Publishing.
Kwon Seung-woo as Kang Han-byeol (s. 2), Assistant Manager of Daehan Noodles' marketing department
Kim Mi-soo as Ja-young (s. 2), Babi's ex-girlfriend
Yoon Yoo-sun as Yumi's mother
Sung Ji-ru as Yumi's father
Others
Choi Min-ho as Chae U-gi (s. 1), Yumi's co-worker and unreciprocated crush.
Ahn Young-mi as Nung-cheol (s. 1)
Lee Sang-yi as Ji Wu-gi (s. 1), Yumi's ex-boyfriend.
Shin Ye-eun as Yoo Da-eun (s. 2), part-time worker at Jeju branch of Daehan Noodles.
Pyo Ji-hoon as Control Z (s. 2), an illustrator who works with Yumi.
Park Bo-eun as Information desk employee (s. 1, ep. 8)
Jung Soo-ji as Si Leon (s. 1, ep. 7–8)
Kim Hye-in as Hong Na-ri (s. 1, ep. 7–8)
Jo Mo-se as wedding guest (s. 1, ep. 13)
Kang Chan-yang as grocery store cashier (s. 1, ep. 11)
Production
Casting
On December 31, 2020, it was reported that webtoon Yumi's Cells published on Naver by Lee Dong-gun from 2015 to 2020 with 3.2 billion accumulated views was being made into a television series and Kim Go-eun was confirmed as the female lead. On March 10, 2021, media reported that Ahn Bo-hyun had received an offer for the part of Yu-mi's first boyfriend, Goo Woong, which was confirmed on April 27 with the final line-up, which also included Lee Yu-bi, Park Ji-hyun and Choi Min-ho.
On July 22, 2021, Jinyoung joined the cast, appearing from episode 8 onwards as Yoo Babi; in the second season the character was promoted to male lead. The second season also features special appearances by Shin Ye-eun, P.O, and Jeon Seok-ho.
The production of the third season was announced on March 31, 2025. Kim Jae-won joined the cast as Shin Soon-rok; new characters played by Choi Daniel and Cho Hye-jung were also introduced.
Filming and adaptation
The first two seasons started production simultaneously. Filming began in April 2021 and ended the following December. While the first season wanted to faithfully adapt the webtoon, with the second one the director and the writers took a different approach, given the polarization of opinions on Babi by the readers of the original work. As Babi flirts with another woman while he is dating Yumi, Jinyoung commented that one of his sisters had asked him if he was really sure about accepting the part and that, with the help of the director and Kim Go-eun, he had tried to show Babi's infinite love for Yumi to try to make people hate him less. Since the third season had not yet been confirmed at the time of filming and wanting to highlight Lee Dong-gun's creativity, the scenes of Yumi's third boyfriend, Shin Soon-rok, were therefore adapted for Babi.
Filming of the third season took place from June to October 2025. Locations included Incheon, Seoul, Suwon and Busan: of the latter, the season features the Ananti at Busan Cove resort, Bosu-dong book street, and Gamcheon village. Considering that the focus on Yumi and Soon-rok in the webtoon was minimal and that it would have been necessary to introduce conflicts not present in the original to extend the story, 8 episodes were produced instead of 14, making the third season more compact and in line with the new panorama of entertainment product consumption.
Animation
Yumi's Cells was produced using a new format which combined live-action and 3D animation. It was the first time such a format was used to produce a TV series while using the Unreal Engine as its source. The 3D animation was produced by Locus Corporation (also known as Sidus Animation Studios), the producer of Red Shoes and the Seven Dwarfs.
Original soundtrack
Reception
Critical reception
Yumi's Cells has been praised for its refreshing and humorous depiction of the daily life of an ordinary office worker, and for giving central importance to Yumi's growth, representing her life, choices and emotional changes over a long period of time. Kim Go-eun's performance was deemed a massive and solid pivot who firmly held the narrative and emotional arc together throughout the whole series.
The first season was praised for its casting, the actors' performances, the faithful adaptation of the webtoon, and the use of 3D animation to depict the cells, although some critics stated that the relatively new attempt to integrate live action and animation could be a barrier for those who were not already fans of the original work. This latter reason was cited as the likely cause of the ratings, which were considered disappointing for its quality.
Yumi's Cells 2 was praised for its greater maturity and evolution in the actors' performances, and was ranked 7th in the best series of 2022 by Cine21, who praised it for not losing its momentum and for realistically weaving together character growth and romance. Indiatoday applauded the chemistry between Kim Go-eun and Jinyoung, but felt that Babi's character had been poorly handled, especially in the second half.
The third season was praised for introducing different situations and relationships than the webtoon without sacrificing its freshness, such as the initial hostile relationship between Yumi and Soon-rok or the Tower of Principles in the last episode. Critics noted that, despite its short length due to the scarce source material and the not particularly special story, the season was solid, brilliant and well-executed. The audience also directed compliments to Kim Jae-won's performance.
Viewership
After the release of the first two episodes of the second season, TVING recorded the highest number of paying subscribers of any of its original dramas, quadrupling the number of subscribers since the premiere of the previous season. They increased by more than 60% from the first to the second week, and the series took first place among all the platform original contents for five weeks in a row.
TVING saw a spike in paying users after the release of the first two episodes of the third season, while episode 1 achieved over 2% in TV ratings and was the most-watched program in its time slot. It held the first spot on TVING and in the ratings for three consecutive weeks, as well as being number one in 81 countries on Rakuten Viki, and in the top 3 on Disney+ in Japan. On the Mongolian platform Inche TV, the third season attracted 1,678 new subscribers and recorded more than 270,000 views in its first week. Despite the low ratings in its home country, it was considered a success for attracting new viewers and generating sufficient buzz.