Parasyte: The Grey

A group of mysterious parasitic creatures fall from outer space and begin using humans as hosts, killing them, and transforming them into unique creatures that can shapeshift their heads into anything. Police squad "The Grey" is formed, led by Choi Jun-kyung. They protect society from parasite attacks and keep the attacks completely off the news and social media. Jun-kyung's husband was one of the first parasites; she now keeps him as a hunting dog, captive under a mask so he can inform the team when any parasite is nearby as Parasites can sense their own kind. Jeong Su-in is a cashier at a supermarket living a mundane life. This changes when she is stabbed by a drunk customer after work. She wakes up in the hospital with the assailant dead. Police officer Kim Chul-min, who had rescued Su-in as a child when she reported her abusive father, checks in on her. Su-in has indeed become a Parasite after the attack, as one had tried taking over her brain when she fell unconscious. She is cornered by two parasites to confirm if she is one of them. This is witnessed by Seol Kang-woo, a small time thug, whose older sister is one of the parasites; his younger sister is missing. The Parasite in Su-in, who Kang-woo names Heidi after Jekyll and Hyde, asks him to inform Su-in of her presence. Heidi could not take complete control of Su-in's body, too busy trying to heal her injured body after the stabbing; hence, she now lives in Su-in's subconscious and can only take over one side of her head and awake to protect her. Jeong Su-in is taken by the parasites to a secluded church where a pastor parasite leads a group of parasites. Kang-woo finds his younger sister's body there. Devastated, he flees with Su-in with the Parasites in pursuit. While inspecting the site, Chul-min finds the key chain he gave to Su-in. He meets her to question her about it but is attacked by Jun-kyung who followed him. Su-in passes out and Chul-min's partner Kang Won-seok kills the hunting dog which is witnessed by Kang-woo. Su-in is taken captive by team Grey despite her results being negative. Chul-min and Kang-woo team up to free her during her transfer. During the transfer, a group of Parasites attacks them and Kang-woo takes the chance and succeeds in freeing her. Chul-min is killed by the Pastor's parasite who later takes his physical form and joins Won-seok to kill all the Parasites at a location with help of team Grey. Su-in informs Jun-kyung about the parasites in the team but she does not believe her initially, however after some investigation she starts suspecting that there are moles in her team. A parasite who uses Kang-woo's older sister's body wants to work together with Su-in to kill the Pastor's parasite and they agree to ambush the Pastor's plan to take over the Mayor's body during festival celebration. At the festival, the Pastor's parasite leaves Chul-min's body and takes over Won-seok. Later, it leaves his head to get into Jun-kyung as the mayor escapes with the help of Kang-woo. Su-in manages to save her, and Jun-kyung kills Won-seok. After reinforcements arrive, Jun-kyung chooses to cover up for Su-in and tells her subordinates that Su-in is not a Parasite. In the aftermath, Su-in and Heidi continue to co-exist with one another while Su-in stays in her job at the supermarket. Kang-woo joins the Grey team and invites Su-in to join him. Back at the headquarters, Jun-kyung meets a self-proclaimed Parasite expert from Japan, who introduces himself as Shinichi Izumi.