While K-dramas are known for their far-fetched plot twists, they look set to take the bizarre to a new level this winter. Delving into the fantasy genre, Korean television is offering two hotly anticipated dramas featuring supernatural creatures -- a mermaid and a goblin -- as lead characters who fall in love with ordinary human beings.

On Dec. 2, tvN will air “Goblin,” the latest project by Kim Eun-sook, the scriptwriter behind the smash-hit military drama “Descendants of the Sun.” Kim, known in the industry as something of a nonstop hit-maker -- she previously wrote the sugary high school romance “The Heirs” -- says she rummaged through historical documents and spiced them up with her imagination to create a fantasy series based on Korean folklore.

“Not much research has been done on dokkaebi (Korean goblins), so there was a lot of room for storytelling,” Kim told reporters at a press conference in southern Seoul on Tuesday.

Actress Jun Ji-hyun stars in SBS’ new drama series “The Legend of the Blue Sea.” (SBS)

The main character of “Goblin,” Kim Shin, is played by Gong Yoo, who has been enjoying a prolific year on the big screen with “Train to Busan” and “Age of Shadows.”

Kim was turned into a goblin and rendered immortal after being impaled in the heart with a sword. Though he underwent no physically grotesque transformation, Kim has become both blessed and cursed with a lifetime of eternity until “the true goblin bride can remove the sword,” according to prophesy.

So Kim leads a torturous existence for nearly a thousand years on earth, until one day in 2016, he meets Ji Eun-tak, a sprightly 19-year-old high school student played by actress Kim Go-eun, who was in the 2016 series “Cheese in the Trap.”

Kim is drawn to the cheery young girl, who has the uncanny ability to see spirits and can summon them by blowing out candles. Eventually -- inevitably -- he will have to make the choice between immortality and love.

“It’s a challenge playing a role that isn’t human,” said Gong. “But I hope people will be able escape from the difficulties of reality through this drama.”

Currently airing on SBS is “The Legend of the Blue Sea,” another fantasy romantic comedy starring A-list actors. “Blue Sea” is also based on Korean folklore and spans multiple time periods.

A still from the trailer for tvN’s new drama series “Goblin” (tvN)

Actress Jun Ji-hyun, also known as Gianna Jun, plays the world’s last surviving mermaid Shim Chung who possesses supernatural powers and has been transported from the Joseon era into current Seoul. She falls in love with Heo Joon-jae, a cold-blooded con man who uses his looks and wit to pull off scams, played by Lee Min-ho.

“Blue Sea” was penned by scriptwriter Park Ji-Eun, who previously wrote the 2013 series “My Love from the Star” featuring actor Kim Soo-hyun as a handsome, all-powerful alien.

“There are largely two reasons people seek the fantasy genre,” according to drama critic Yoon Seok-jin. “The fantasy world can either offer a new set of moral rules different from those of the real world. It can also solve things that can’t be solved in the real world.”

In recent fantasy series, including “My Love” and last year’s “The Girl who Sees Smells” -- which features a girl able to trace smells as visible colors and shapes -- the heroes possess supernatural abilities that are used to unravel unsolvable problems, Yoon said.

“This can reflect viewers’ frustration with the established systems,” he added.

The fantasy genre, meanwhile, poses the risk of running amok.

“There’s the danger of everything being explained away with supernatural phenomena,” said Yoon. “A set of rules need to exist within the fantasy world as well.”

By Rumy Doo (doo@heraldcorp.com)

Related article: ‘The Legend of the Blue Sea’ more popular than ‘Descendants of the Sun’?