This is a bittersweet moment for fans of Overlord season 4, as the show has been renewed for the next season but it will not be arriving this year and we may have to wait a long time to see this Manga series return again.
Not officially recommissioned
Enough material not available
Another reason why it is taking so long for the production house to begin season 4 is that there is simply not enough material to cover for the upcoming season. The author of the series Kugane Maruyama has not written anything new and the existing anime has been covered till season 3.
At the time of writing this article, there are 13 volumes of the Overlord manga series, and nine of them have been used for the production of the first three seasons of the show. Four volumes are simply not enough to cover an entire season. So the production house is forced to wait for Kugane to write the story ahead.
The animation studio is also severely understaffed and that could be another reason for the delay in the production of the Overlord season 4. Fans can expect Overlord to return in 2020 or 2021.