The one-of-a-kind prototype of Holo falls into Han So-yeon's solitary life, eager to help with anything she needs — if she will allow him.
Seeing she has a crush on her co-worker, Holo offers to be So-yeon's dating coach. Ko Nan-do monitors their growing bond from his lab.
Nan-do moves in next door to So-yeon, convinced that being with her has broken Holo, and determined to do whatever it takes to fix him.
Conflicted about her feelings, So-yeon tries to distance herself from Holo. Baek Chan-sung sends his men after her glasses.
When So-yeon wakes up in the hospital, something's changed about how she sees Holo. He and Ko Yoo-jin urge Nan-do to reveal himself to her.
So-yeon realizes that loving Holo means certain relationship norms are out of their reach. Nan-do deals with unwanted attention from the police.
In danger from those attempting to steal the prototype, So-yeon agrees to stay at the lab. Nan-do puts on his best impression of Holo.
Hoping to restore Holo, So-yeon sets out to jog his missing memories — and discovers a history with Nan-do that she hadn't figured out yet.
No one understands exactly how Holo came back. As the lab prepares to make the product public, Nan-do hands So-yeon the eyeglasses for good.
Faced with little choice, Nan-do hands over his lab to its rival company. So-yeon meets the new Holo, who feels like a stranger.
While Holo proves to be a huge hit with the public, Nan-do hides himself away with a plan to return the original Holo to So-yeon.
Nan-do breaks into the lab to save So-yeon, who's had a revelation about what happened to his mother. Holo defies Baek Nam-gyu's expectations.