That Time I Got Reincarnated as a Slime

The That Time I Got Reincarnated as a Slime watch order starts with all 24 episodes of the first season from studio 8-bit, followed by a set of OVAs that expand Rimuru's world. Watch Episodes 1-24 first to get the full arc, then move on to the side content: Veldora's Journal, the comedic "Hey! Butts!" OAD, "The Tragedy of M?", and the three-part Rimuru's Glamorous Life as a Teacher OADs. These OVAs are lighthearted extras that sit best after the main episodes rather than between them, so you finish the core story before enjoying the bonus shorts. If you are wondering where to start, begin at Episode 1. This page lays out the correct order including all the OVAs so you can track the first season and its side stories in sequence, then continue on to later seasons once you have cleared this foundational run of the isekai.