In Season 1 of Gyeongseong Creature, Tae-sang and Chae-ok are put through the emotional grinder. Their main focus is to battle the Japanese occupation of the Joseon region in the 1940s with a handful of rebels. At the core of their mission is tackling an oppressive movement that holds Korean prisoners in an experimental hospital. There, Chae-ok's mother, Seishin, was turned into a merciless monster.
Source：https://www.cbr.com/gyeongseong-creature-season-1-burning-questions/
