Overlord Prologue (2nd Part) is a side story in the Overlord series. It was released on February 24, 2016, in Box 6 of the Blu-ray & DVD Collection.
The newly formed guild, Ainz Ooal Gown assembled at Piercing Crystal Plains at the outskirts of Helheim. In preparation for their raid on the newly discovered dungeon, the Great Tomb of Nazarick, twenty-seven guild members are present. Members of Ainz Ooal Gown, Nubo, Flatfoot, and Nishikienrai report that there is no one spying on them and that the surroundings are clear of enemies. After the guild made their equipment preparations, they proceeded to the Grenbera Swamp. Once they are able to bypass several minor obstacles, the guild finally comes before the entrance of the Great Tomb of Nazarick. Finding no general threats in the vicinity, Blue Planet conjures a makeshift base for the guild to plan their next course of action.
When they are ready, Punitto Moe begins to assign them to different parties for the dungeon expedition. However, Tabula argues against him, alongside some other members believing to stay in their current parties. The decision is given to Momonga to decides who then holds a vote. Through majority vote, the guild remains in its current parties, and policy is set to have majority vote rule in favor for any event for Ainz Ooal Gown.
As Ainz Ooal Gown enters the tomb, Punitto proceeds to assign team assignments, a complete deviation from Momonga's plan, but the violation is mostly ignored. Momonga is assigned as a wild card in a group composed of Ulbert Alain Odle, Warrior Takemikazuchi, Bukubukuchagama, Yamaiko, and Nishikienrai. The guild is divided into five parties. Upon going deeper into the tomb, their presence initiates the dungeon's defenses, which led to the beginning of the raid. Momonga's group is attacked by four undead but dispatch them.
The various parties scattered across the floors on Nazarick, reporting on the fact that they are fighting Bosses of varying types. In particular, Momonga's group come across the final boss, which is an Asura. Nonetheless, the group manages to defeat the boss and the other parties were also successful in carrying out their task as well. In other words, after the boss's defeat, Momonga's group is soon joined by the others.
For their success in conquering the Great Tomb of Nazarick, the guild is awarded a World Item, the Throne of Kings. In addition to that, they are given the ownership rights of the tomb. To commemorate the moment, Momonga sits upon the throne as his guildmates gather around to take a picture.
- A World Item called Throne of Kings is introduced in this side story. Thus, it finally affirmed the throne's identity of which Ainz is usually seated upon in front of the NPCs.