From left, director Park Kun-ho, scriptwriter Lee Soo-yeon, actors Lee Jun-hyuk and Park Sung-woong greet audience during an open talk session for their latest production "Dongjae, the Good or the Bastard" at Busan International Film Festival (BIFF) in Haeundae District, Busan, Oct. 5. Yonhap

The universe of tvN's 2017 hit series "Stranger" will expand in a 10-part spin-off series focused on Seo Dong-jae, in a rare move to spotlight a supporting character in a sub-series.

The upcoming series "Dongjae, the Good or the Bastard," directed by Park Kun-ho, centers on the controversial prosecutor Dong-jae, played by Lee Jun-hyuk. With a tarnished reputation and blurred moral lines, the character was both loved and hated by audiences in the original series.

"I aimed to tell a different story, while still sharing the same universe of the original work," the director said at a press conference in Seoul on Tuesday.

He described Dong-jae as being disliked in the first season (2017) and "somewhat rooted for" in the second season (2020) of the original "Stranger" series. Despite the shift, Dong-jae remains an ambiguous figure, constantly teetering between good and bad, as reflected in the title of the upcoming show, he said.

"Portraying the contrasting sides of a character isn't easy," he said. "But I am very happy with the title, as it captures the essence of Dong-jae and reflects the perspectives of the fans."

Actor Lee admitted he felt immense pressure when he first heard about the spin-off of the popular original, but his outlook improved after seeing many positive reactions to the news.

"I worked hard to bring something new to this spin-off, compared with the original," Lee said, adding, "I'd liken the spin-off to a dessert and the original to the main course at a fine dining restaurant."

The spin-off follows Dong-jae's precarious and somewhat comical journey as he attempts to clear his name and be recognized for who he is now, rather than being defined by his past actions. However, his efforts are complicated by construction company CEO Nam Wan-seong, played by Park Sung-woong, who is determined to unearth Dong-jae's previous misdeeds.

The director said viewers will be entertained by watching how Dong-jae navigates challenging situations and will find themselves sympathizing with him along the way. He also noted the rare kind of spin-off in Korea with a focus on a supporting character.

"While the original series sends political and social messages, this one focuses more on the individual characters," he said. "Many can relate to Dong-jae, who, despite being full of self-doubt and an intense desire to climb the social ladder, remains deeply human."

The highly acclaimed original crime thriller "Stranger," starring Cho Seung-woo and Bae Doo-na, follows a prosecutor with no ability to feel empathy as he tackles a gruesome murder case and political corruption, alongside a female detective. The original scriptwriter, Lee Soo-yeon, is involved in the spin-off as a creative director.

Wrapping up the press event, actor Park joked that he's already anticipating another spin-off centered on his character.

"I've even come up with a title: 'Wan-seong, the Bad or the Worse."

The series is set for release on Tving on Thursday. (Yonhap)