Kim Min-kyu, a wealthy young man with a severe allergy to humans, meets Jo Ji-ah, a struggling inventor who is recruited to help him test a new robot.

Ji-ah pretends to be the robot to help Min-kyu overcome his allergy, and as they spend time together, he starts to develop feelings for the robot.

Ji-ah struggles with the guilt of deceiving Min-kyu, but she continues to pretend to be the robot, and they go on a date together.

Min-kyu invites the robot to his house and becomes closer to Ji-ah, not realizing that she is a human.

Min Kyu hugs Aji 3 and tells her that she is all he needs; Baek Gyoon punches him in the face and brings Ji A home; he tells her that her part-time job is over.

Min-kyu discovers that the robot can speak and starts to suspect that it might be more than just a machine.