The drama is based on the manga, but will tell its own new story.
Jeon So-nee is cast in the role of Jeon Soo-in, a woman who is attacked by a Parasyte but lives a strange coexistence with it without losing control of her brain.
Koo Kyo-hwan is cast as Solu Gang-woo, a man who chases after Parasyte to find his missing sister.
Lee Jung-hyun is cast as Choi Jun-kyung, whose husband was killed by Parasyte and who becomes the leader of "The Grey," a special unit that fights Parasyte.
Yeon Sang-ho is directing the drama, and is also writing scripts with Ryu Yong-jae.