Managed by a complex network of cells, every human being on earth is animated by an invisible operating system that, in most cases, we are completely unaware of. Although humans don't spend much time thinking about how they function on a daily basis, the cells of the human body work tirelessly, playing their part in preserving the life and health of their host. That's why, on the surface, Kim Yu Mi may look like every other active woman in the world, but beneath this ordinary facade lies something truly extraordinary.