Inside Yumi, a 32 year old office worker, lives thousands of tiny blue-hooded cells that control her every mood, thought, and action.
Yumi likes her younger colleague, Wook. A lot of things prevent her from pursuing him like being insecure about her age and her love rival, Rubi. Though, Yumi's cells are willing to do anything for Yumi's happiness.
Wook seems to be interested in her too; wanting to talk to her and go out with her. Yumi becomes overjoyed at the thought that he would confess his love. But it's all a setup for him to ask her if she wanted to go on a blind date with his friend. Yumi also finds out that he is homosexual -- so she didn't even have a chance.
Yumi becomes depressed over this, and her blind date with Wook's friend, Woong, seems to be a total bust.
As Yumi becomes more and more stressed, she faints, and Woong carries her and runs to a nearby hospital. He buys her a hoodie and when Yumi wakes up, she starts to take more interest in Woong.
An introverted girl who likes to eat. She likes Wook, but he turned her down. She got set up to go on a blind date with Wook's friend, Woong. Initially, she didn't like him, but after he rushes her to the hospital, she starts to take interest in him.
Her cells wear a bright blue suit with a hood.
He is younger than Yumi and works in the advertising department. He also confessed to liking a guy.
Yumi's colleague and love rival. She is manipulative and very determined to get Wook's love. Though, she doesn't know that Wook is homosexual.
Wook's friend and gaming nerd. Before dating Yumi, he sat around playing video games all day and generally was a slob. After meeting her, he grew to like her, showing his dedication by carrying her to a nearby hospital after she fainted.