Overlord is an atypical Isekai anime where the hero's background in the real world is not mentioned at all. That is ok, because this anime thrives entirely on the character that the main protagonist possesses in the New World.
I really enjoyed the first 3 seasons of the anime, although other reviewers criticized the lack of a backstory.
The fourth season though is by far the weakest season of Overlord.
I watched it within two days, like the seasons before, but by no means understood everything. This includes in particular references to the "Holy Kingdom", whose arc was skipped in the anime, as I only found out later. According to Wikipedia, the fourth season covers light novel volumes 10, 11 and 14. A movie was supposed to cover the Holy Kingdom Arc (light novel volume 12 & 13), but so far I haven't been able to find any information about it. Maybe it hasn't appeared yet - or perhaps it never will appear at all.
I really enjoyed the first 3 seasons of the anime, although other reviewers criticized the lack of a backstory.
The fourth season though is by far the weakest season of Overlord.
I watched it within two days, like the seasons before, but by no means understood everything. This includes in particular references to the "Holy Kingdom", whose arc was skipped in the anime, as I only found out later. According to Wikipedia, the fourth season covers light novel volumes 10, 11 and 14. A movie was supposed to cover the Holy Kingdom Arc (light novel volume 12 & 13), but so far I haven't been able to find any information about it. Maybe it hasn't appeared yet - or perhaps it never will appear at all.