The core cast in 'One Dollar Lawyer' rotates around the protagonist, Cheon Ji-hun. He's the titular lawyer who charges only one dollar, but his real motivation is a personal quest tied to his past. The narrative hinges on his conflict with Baek Ma-ri, a skilled but very by-the-book prosecutor from a wealthy family. Their adversarial relationship, full of bickering and legal clashes, slowly develops a weird mutual respect and, eventually, a deeper connection.
Beyond that central duo, there's the supporting team at Ji-hun's ramshackle office. Seo Min-woo, a young lawyer Ji-hun ends up mentoring, provides a more earnest, emotional counterpoint to Ji-hun's cynical exterior. Min-woo's growth is a big part of the story. The chairman of a huge conglomerate, whose identity is initially hidden, serves as the main overarching antagonist. A lot of the early mystery involves figuring out who he is and how he's connected to Ji-hun's tragic backstory, which involves a lost loved one. The series does a good job making even minor case-of-the-week clients feel memorable, which is a strength of its episodic structure.