Choi Seung Hyun (T.O.P/Seunghyun) Seunghyun A passionate young entrepreneur who possesses a high emotional intelligence and has great knowledge in mechanics due to his father's influence in his car centre. He was recruited by the Santa Maria robotic team to pretend as T.O.P. He has an IQ of 94. T.O.P: The world's most advanced humanoid robot among the artificial intelligence models released.

Park Sandara (Dara) The greatest shareholder of the country's largest financial company with an IQ of 159 but is a "human allergy" patient who cannot be in contact with people. As the business contract states, she is the owner of T.O.P, the robot that was sent to her to be tested. She develops feelings and falls in love with Seunghyun who pretends to be T.O.P after the malfunction of the robot.

Lee Min Jung (Professor) Seunghyun’s ex-girlfriend who is a world-renowned genius robotics professor and is the creator of the android named T.O.P. She created T.O.P based on her ex-boyfriend, Seunghyun.

Santa Maria team

• Park Bom
• Kang Daesung
• Lee Seung Hyun

People around Min-kyu

• Dong Young Bae as Doctor
• Teddy Park as Butler Sung

KM Financial

• Park Shin Hye - Dara’s childhood best friend who is the CEO of the company.
• Kwon Ji Yong – Dara’s childhood friend and first love.
• Park Min Hyuk – Shinhye’s father and the president of the company.
• Kwon Sang Woo – Ji Yong’s father one of the founders of the company.
• Kang Doo Jun - KM Group Managing Director.

People around Ji-ah

• Choi Dong Wook as Seunghyun’s older brother who is the research team leader of KM Financial.
• Yoo In Na - friend who is a cafe owner.
• Park Han Byul – Seunghyun’s schoolmate friend and Dongwook’s wife.
• Choi Yeon Jun Hanbyul and Dongwook’s child.

Plot

Sandara Park lives an isolated life due to a severe allergy to other people. She develops extreme rashes that rapidly spread throughout her body once she makes any form of skin contact. Choi Seung Hyun is a man who is trying to make it in life by creating his own businesses. However, after an encounter with Dara, he ends up pretending to be a robot in place of the supposed T.O.P robot. The T.O.P robot was developed by Seung Hyun’s ex-girlfriend, professor Lee Min Jung and her team. The robot was meant to be tested by genius Dara, however an accident caused the robot's battery to malfunction. As Min Jung modeled the robot after Seung Hyun, the team ends up recruiting him to take the place of T.O.P.