Yumi is a 30-year old, ordinary woman who struggles with expressing her feelings. Told from the perspective of the many brain cells in her head, she experiences growth in both her love life, her career, and finds happiness in the small joys of everyday life.
Controlled by a complex network of cells, each and every human on the planet is kept running by an unseen operating system that is, for the most part, completely ignored. Though humans never give much thought to how they manage to function, day in and day out, the cells within the human body are constantly at work, doing their part to keep their humans alive and well. This is why, on the outside, Kim Yu Mi may appear to be just like every other single working woman in the world, but underneath that ordinary exterior lies something truly extraordinary.
Having recently suffered a painful breakup, Yu Mi’s love cells have fallen into a deep coma. While the surrounding cells work hard to revive their fallen compatriots, Yu Mi spends her days stuck in the grind of everyday life. With a heart still broken and no romantic prospects, Yu Mi’s love cells might have been in serious trouble had it not been for the sudden appearance of Koo Ung. An emotionally stunted game developer, Koo Ung, has no idea how to express his true feelings, but after meeting Yu Mi, he finds himself wanting to try. With his own love cells unexpectedly sparking Yu Mi’s back to life, things between the two start to get interesting. With both Yu Mi and Koo Ung’s cells working overtime, the two find themselves drawing ever closer.
But will the efforts of this small collection of cells really be enough to bring two hearts together forever?