The movie "Alienoid" is a South Korean science fiction film directed by Choi Dong-hoon. The story takes place in the Goryeo era and follows the adventures of a warrior named Moo-ri (played by Kim Ki-woo) who is tasked with capturing an alien who has been sent to Earth to collect a powerful artifact. However, things take a turn when Moo-ri discovers that the alien, named Gwon Jae-seok (played by Kim Su-an), has a peculiar condition that makes him switch bodies with a modern-day high school student, Yi-han (also played by Kim Ki-woo).