Witness And Superman - S1.E6

Sang-hyuk and Jae-hee learn that Baek-ryeon was a witness to the Inwangsan disappearance incident. In order to protect Baek-ryeon, Sang-hyuk chases down the criminal like her knight in shining armor. Baek-ryeon is happy when Sang-hyuk protects her like Superman and doesn't get hurt even after the intense physical fight, and she gets very curious about his true identity.