While others not only boarded but also ride the Train to Busan (title of the live action picture), we also get this animated feature which plays in the same "universe" as the other movie. Having said that, you do get different characters in the starring roles and a movie that does indulge in what would happen if a zombie epidemic hit a city. Relationships between characters and story-lines begin to unfold, as much as some of the human psyche is.
It's a nice little add-on or spin off to Train to Busan, but it's not a must watch to get the other movie or vice versa. It's also very explicit with its violence as is the other movie and we get a lot of action scenes too. It does get a bit cliché here and there (father/daughter story) and has some minor flaws along the way. Even so it is more than entertaining to watch