Kim Min Kyu is the majority shareholder of a financial company. He suffers from a "human allergy" that prevents him from interacting normally with other people. He takes an interest in a robotics project called Aji-3, created by the Santa Maria robotics team. The team is led by Hong Baek Gyun, the inventor of Aji-3 and a world-renowned robotics professor. He modeled Aji-3 after his ex-girlfriend, Jo Ji Ah, a struggling inventor who also works as a personal shopper to make ends meet. Just as Kim Min Kyu is about to test the robot, an accident causes the robot’s battery to malfunction. Hong Baek Gyun begs Jo Ji Ah to take Aji-3’s place and pretend to be the robot in order to secure funding from Kim Min Kyu. But Aji-3 becomes the closest thing to real human connection that the lonely Min Kyu has ever experienced.