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.
Now a successful web novelist, Yumi has achieved her professional dreams but finds her "cells" have grown dormant, leaving her feeling indifferent. Her quiet life is disrupted by her new editor, Shin Soon-rok, whose rational nature unexpectedly reawakens her emotions. As Yumi navigates her connection with Soon-rok, she is also pursued by a charming fellow writer, forcing her to decide which path will lead to the fulfillment she seeks.