Grimgar of Fantasy and Ash

The Grimgar of Fantasy and Ash watch order is a single 12-episode season with one OVA tucked inside it. Start with Episodes 1-2, then watch the Staking Our Youths on the Bath Wall - One More Centimeter OVA before continuing with Episodes 3-12. The OVA is a light side-story that fits neatly after the opening pair of episodes, which is why it slots in there rather than at the end of the run. If you'd rather stick to the main plot, you can watch all twelve episodes straight through and save the OVA for later, but the intended chronological order places it between Episodes 2 and 3. Either way, Episode 1 is where to start, and this covers the complete anime run including the OVA for the full A-1 Pictures adaptation.