Ko Hyun-jung is embracing the darkness in SBS’s new thriller "The Mantis: Original Sin" ― and she’s revealing the extreme steps she took to become a serial killer.
Premiering Friday, Sept. 5 at 9:50 p.m. on SBS, the high-density crime drama tracks a string of copycat murders more than 20 years after the original “Mantis” was caught. To crack the case, a detective is forced into an unlikely alliance with the person he’s hated his entire life ― his mother, the infamous “Mantis.”
The series has been buzzing ahead of launch thanks to Ko’s drastic transformation as Jung Yi-shin, the murderer so brutal she earned the “Mantis” moniker. Teasers show the star in a death-row uniform with a bloodless pallor, a chilling smile, and dagger-sharp eyes ― fueling sky-high anticipation for her no-holds-barred performance.
In a sit-down, Ko unpacked who Jung Yi-shin is and how she built her from the ground up.
“Jung Yi-shin murdered five men and became known as the ‘Mantis,’ but she’s also a mother,” Ko says. “She’s not someone you can sum up in a sentence. One moment she radiates a chilling presence that makes the nickname instantly believable; the next, there’s this vacant, almost detached look that feels utterly hollow.”
“The second you decide, ‘Ah, that’s who she is,’ she shatters your expectations,” she adds. “While acting, I kept that unpredictability front and center to preserve her mystery ― and to keep the tension humming.”
That duality meant Ko had to go all in ― and get meticulous ― to find the character’s edges and keep audiences guessing.
“To maximize the thrills of a high-intensity crime drama, I felt it was crucial to spark curiosity about Jung Yi-shin,” she explains. “Instead of signaling feelings with obvious expressions, I leaned into small, ambiguous beats that could pull viewers into a swirl of doubt. I talked a lot with director Byun Young-joo on set to fine-tune those nuances.”
Her physical transformation was just as deliberate. “To highlight the character’s stark, drained vibe, we stripped back hair and wardrobe, keeping everything as bare as possible,” Ko says. “Because she’s been incarcerated on death row for a long time, we added details like age spots and wrinkles to show time’s imprint.”
Ko’s thoughtful, fiercely committed approach underscores her affection for both the show and the character. With an all-time great like Ko Hyun-jung throwing herself into the ‘Mantis,’ expect a serial killer portrayal that leaves a mark.
"The Mantis: Original Sin", SBS’s new Friday-Saturday drama, premieres Sept. 5 at 9:50 p.m. following "The Winning Try."
(SBS Entertainment News | Kang Sun-ae)