Yeon Sang-ho became a household name in the dark fantasy genre with his films and series like “Train to Busan” (2016), “Hellbound” (2021-) and “The Bequeathed.” Once again, the director offers a spin on the genre with Netflix’s upcoming original horror thriller series “Parasyte: The Grey.”

However, the show stands out from Yeon’s previous explorations of the apocalypse or the supernatural. This time, Yeon's work dips into a philosophical theme — coexistence.

“Parasyte: The Grey” is based on the Japanese horror manga series “Parasyte” by Hitoshi Iwaaki. Yeon, who directed and co-wrote the show, reinterpreted the original with a new plot adapted for a Korean context.

“Parasyte: The Grey” follows Su-in, played by actor Jeon So-nee, who is forced to share a life with a parasitic creature named Heidi that partially inhabits her body. The two are likened to Dr. Jekyll and Mr. Hyde, as Su-in and Heidi are polar opposites.

“I would describe Heidi to be an extreme T [thinker],” Yeon said during a press conference for the show at the Seoul Dragon City in Yongsan District, central Seoul, on Tuesday.

“Heidi is void of emotion, but since Su-in is human, she is more sentimental and falls closer to the F [feeling] type," Yeon said, using the popular Myers-Briggs personality test to explain the characters. "This story is about how these two learn to understand each other.”

“Before Heidi comes into her life, Su-in used to live in solitude,” Jeon said. “Life was dull for her, but since a different being came into her, she learns that there’s more to life.”

The show also stars Koo Kyo-hwan, Lee Jung-hyun, Kwon Hae-hyo and Kim In-kwon. Koo plays Kang-woo, who searches for his lost sister among the parasites. Kwon and Kim are police detectives who try to protect Su-in and are “super relatable,” Yeon said.

Arguably the most distinctive change to Yeon’s version of “Parasyte” is the introduction of Lee’s character, Jun-kyung, a criminal profiler who hunts parasitic creatures after her husband disappears. She is the head of The Grey, a task force team whose goal is to exterminate the parasites.

“Jun-kyung is definitely not a normal character,” Lee said. “She kills parasites for entertainment. I had to build muscles in just three months after giving birth for this role. I practiced the action scenes with our martial arts crew.”

The main cast, especially Jeon, Koo and Lee, revealed that they were fans of the Japanese comic, collectively agreeing that the reason why they decided to work on “Parasyte: The Grey” was because they were intrigued by Yeon’s new storyline.

“Before I started my career in animation, ever since I was little, the original ‘Parasyte’ comic was like the bible among me and my friends,” Yeon said. “I was such a fan that I started imagining what more I could create from it. I sent a handwritten letter to Iwaaki, and thankfully I got his blessing. For anyone who is going to watch my show — I highly recommend reading the original books first. They will blow your mind.”

“Parasyte: The Grey” premieres on Netflix on April 5.

BY SHIN MIN-HEE [shin.minhee@joongang.co.kr]