The first episode of this popular horror/sci-fi anime is titled "The Metamorphosis." It introduces Shinichi Izumi, whose hand is taken over by an alien parasite.
Alien: Earth recap - season 1, episode 3, "Metamorphosis" - AV Club [S1E1] Metamorphosis
Several series have a premiere episode titled Based on the most common reviews for shows with this [S1E1] title, H2O: Just Add Water (2006) The first episode of this popular horror/sci-fi anime