Oh Seung-ha, portrayed by Ju Ji-hoon in The Devil, is a character with a deeply tragic and complex backstory. As a child, he witnessed the brutal murder of his brother, which left him traumatized and filled with a burning desire for revenge. This traumatic event shaped his entire life, leading him to meticulously plan and execute a series of murders to avenge his brother’s death. Despite his outward appearance as a kind and altruistic lawyer, Seung-ha is an expert manipulator, using his intelligence and legal expertise to orchestrate his revenge without arousing suspicion. His duality makes him a compelling and multifaceted character, as he navigates the fine line between justice and vengeance.