Kim Mingyu is the largest shareholder of a financial company. He suffers from a "human allergy", preventing him from normal interactions with other people. He becomes interested in a robotic project named Aji 3 created by the Santa Maria robotic team. The team is headed by Hong Baekgyeon, inventor of Aji 3 and world-renowned robotics professor. He modeled Aji 3 after his ex-girlfriend, Jo Jia, a struggling inventor that also works as a personal shopper to make ends meet. Just when Mingyu wants to test the robot, an accident causes the malfunction of the robot's battery. Baekgyeon begs Jia to take the place of Aji 3 and pretend to be the robot so they can get funding from Mingyu. But Aji 3 becomes the closest thing that the lonely Mingyu has to real contact with another person.