Netflix has unveiled the trailer for its upcoming South Korean action film Mantis, a spin-off of the 2023 hit Kill Boksoon. The movie is scheduled to premiere on Netflix on Friday, September 26, 2025, at 4 pm KST. Set in the same world as Kill Boksoon, the film centers around a highly skilled assassin named Han-ul. After returning from vacation, he discovers that the underground society of contract killers has descended into disorder. The story follows his reentry into the fractured order as rival killers compete for dominance.The official trailer, released on August 27, 2025, offers a first look at the violent power struggle in the assassin industry. It highlights the return of Mantis and teases intense action sequences alongside the clash between old and new players in the world of killers. The cast features Yim Si-wan in the lead role, alongside Park Gyu-young and Jo Woo-jin.Sharing the release date and the trailer of the movie, Netflix wrote:"Yim Si-wan, Park Gyu-young, and Jo Woo-jin star in MANTIS, a new film set in the world of KILL BOKSOON. Coming September 26. The secret society of contract killers falls into chaos, unleashing a new breed of assassins. With old rules in ruins, who dares claim the shadows?Netflix’s Mantis spin-off explores power struggles in the Kill Boksoon universe, premiering September 26Set in the same world of contract killers, of Kill Boksoon, Mantis shifts its focus to power struggles and fractured loyalties within MK Ent. - a secretive organization at the heart of the assassin industry. The film introduces Han-ul, who is codenamed “Mantis,” a top-tier assassin.Once referenced in Kill Boksoon as having “gone on a vacation,” the character steps into the spotlight with his own narrative this time. He returns from an extended absence to find the underworld in turmoil following the death of MK Ent. chief, Cha Min-kyu.Returning to MK Ent., Han-ul reconnects with Jae-yi, an old trainee friend and fellow assassin. Jae-yi has been dismissed from the organization after falling out with its leadership. Despite her lethal reputation, she carries conflicted emotions toward Han-ul, shaped by their long history together.Meanwhile, once Mantis’s mentor, Dok-go is a retired assassin and one of MK Ent.'s original founders. He resumes leadership of the company after Cha Min-kyu’s death, aiming to restore order while seeking to bring Mantis back into the fold. His return, however, comes with motives of his own.chai @_chaibooLINKdark siwan is my fave genre, you can’t change my mindPreviously, Kill Boksoon followed Gil Boksoon’s struggle to balance her life as both - a mother and a professional killer. However, Mantis places emphasis on internal rivalries within the assassin hierarchy. With its combination of action, psychological tension, and character-driven drama, the upcoming project is expected to expand the assassin universe introduced in the 2023 film.Yim Si-Wan in the trailer (Image via YouTube/@netflixkcontent)Yim Si-wan (Summer Strike, Hell Is Other People, Emergency Declaration) takes on the role of Han-ul, while Park Gyu-young (Sweet Home, Celebrity) plays Jae-yi. Both actors have appeared in Squid Game seasons 2 and 3, though they have not shared screen time. Additionally, Jo Woo-jin (Harbin, Gangnam B- Side, Narco-Saints, Happiness) joins the cast as Dok-go.The teaser trailer for the film opens with the voice of Cha Min-kyu (Sul Kyung-gu), the late CEO of MK Ent., echoing the rules as Han-ul returns. The rules are, never kill minors, only accept jobs sanctioned by the company, and always attempt the missions assigned.ً @kdramaswrldLINKsiwan and park gyuyoung in a new project together i can't wait !!!!The footage transitions to glimpses of Mantis and Jae-yi during their past training and missions. The tension escalates in the closing sequence, where the two face off on a rooftop. Jae-yi taunts:“Am I not above you now?”To that Han-ul responds:“Is that why you wanted to kill me?" and "What took you so long?”Between these moments, bold text flashes across the screen noting:“A NEW GENERATION OF RISING KILLERS.”The trailer sets up the central conflict among three key figures, Han-ul aka Mantis; Jae-yi, and Dok-go.The movie is co-written by Byun Sung-hyun, director of Kill Boksoon, and Lee Tae-sung, who eaworked as an assistant director on Kill Boksoon and The King. Lee makes his feature directorial debut with this project. Production is handled by SEE AT Film Co., LTD, the company behind Love and Leashes, and Kingmaker.