Within four days of its premiere, new SBS drama The King: Eternal Monarch has become one of the most loved Korean dramas world-wide. All the credit goes to screenwriter Kim Eun Sook and its cast members, including Lee Min Ho, Kim Go Eun and Woo Do Hwan. A thrilling story and excellent portrayal of characters have kept viewers glued to the screens.

The lead cast members of the mini-series shared some details of how they prepared for their special roles in the historical fantasy thriller during an online press conference last week. Some of the actors also spoke about the various challenges they faced while portraying dual roles in the drama.

Lee Min Ho as Emperor Lee Gon

Lead actor Lee Min Ho, who portrays Emperor Lee Gon in the mini-series, said he had to do a lot of research while preparing for the role. Apart from going through several books written by mathematicians, he also looked into lectures by physicists to understand their characters. According to him, those who are interested in natural science tend to be serious and take some time to solve problems. But they are also very sincere, he added.

The Legend of the Blue Sea star said the only reason he decided to be a part of the project is screenwriter Kim Eun Sook. In addition to the "weight and influence" of her name, he revealed that the "trust and faith" he puts in her helped him choose the drama as his comeback project.

Lee Min Ho
A character poster of Lee Min Ho in The King: Eternal Monarch. SBS

Kim Go Eun as detective Jung Tae Eul

Kim Go Eun, who appears in twin roles – as detective Jung Tae Eul in Republic of Korea and criminal Luna in Kingdom of Corea – said she challenged herself to portray dual roles. Though the cast member did not reveal much about her role as criminal Luna, she said Jung Tae Eul is a person who "takes action using her intuition, rather than solving problems on her head".

The actress also asked viewers to closely watch every scene because it is a "fun mystery drama" with a lot of details hidden in every scene. "It is a story about parallel worlds, and there are a lot of details in it. There has never been a drama with such various double roles," she added.

Kim Go Eun
A character poster of Kim Go Eun in The King: Eternal Monarch. SBS

Woo Do Hwan as Jo Young and Jo Eun Seob

Another cast member who portrays dual roles in the fantasy thriller is Woo Do Hwan. He plays the role of Emperor Lee Gon's bodyguard Jo Young in the Kingdom of Corea and a public service officer named Jo Eun Seob in the Republic of Korea. The actor revealed that it was really hard for him to portray dual roles and screenwriter Kim Eun Sook helped out.

"It was very pressuring to play dual roles. Both are great roles, but the dialect was burdensome. The writer encouraged me to trust and follow her without worrying. I'm doing my best not to cause trouble. I will show a bright side that I have never shown in my previous works," the actor said.

The King: Eternal Monarch revolves around the life of a young Emperor named Lee Gon, who ends staying in a parallel world. The story focuses on his relationship with detective Jung Tae Eul and how the two help each other. The fantasy thriller airs on SBS Mondays and Tuesdays at 10pm KST.