According to author Kugane Naruyama , volume 17 of the Overlord Light Novel will conclude the series. This volume is scheduled to be released on March 12th .
The author had previously given signs on his Twitter that he intended to finish the work in volume 17.
Overlord also had a successful anime 2015 , with the first season having a total of 13 episodes .
The 3 seasons are officially available on Crunchyroll , and a fourth season confirmed
Source: ANN