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GA Non-Canon: REMINDER! This page is considered as among one of the many pure game contents found exclusive in Mass for the Dead only. It includes the new standalone characters that had a first-time appearance in the game. Meanwhile, the old characters had a different role and fate than from the main storyline in the official books. For that reason, it has no connections to the canon story materials of Overlord Light Novel series. The content that you had read here are based on the Overlord mobile game.

Mysterious Island is a tentative name for a deserted island located somewhere in the New World that appears in the Mass for the Dead game.


Two hundred years ago, this island was a base of operations for pirates. However, their island hideout was discovered and a battle took place in their hidden port. While they fought the attackers, through intention or accident, they broke the mechanism that opened the door to the cave passage.

The pirates attempted to make out to sea with their treasure, but apparently a Giant Mollusk had entered through the waterway and into the small port. In the ensuing chaos, the pirates and attackers were all killed when the monster broke in and destroyed the ship.


Mass for the Dead Arc[]

Main article: Mass for the Dead Arc

In the present, Momonga was conducting an experiment to connect a [Gate] to the Mine Dungeon to deliver resources to the damaged Great Tomb of Nazarick. Momonga sent a Skeleton to test it but discovered that the [Gate] connected to the island instead. While it was a failure, the summon, had found a scroll with a map of the island.

Interested in this find, after Pandora's Actor estimated the artifact to be over a hundred years old, Momonga sent the Pleiades, Slimeko and the game's protagonist to investigate. The maids equipped with swimsuits explored the island, but even though they split up, they were unable to find any clues around the perimeter of the island save. Turning to into the jungle, the maids and their allies discover a well indicating that the island was inhabited.

The team goes to the last place on the island they had not checked, a deep cave near the reefs. Reaching the reef and the cave, Entoma Vasilissa Zeta uses her insects to do a survey, however they reveal to her that something inside the cave is obstructing a passage. Inside the cave, they find it goes deeper then expected, and discover the obstruction. Initially thought to be a wall to turns out to be a Large Crustacean. After killing the creature, the cave is revealed to go deeper. What they find is a dead end, until they find that the wall is fake. Breaking it down, they find a section of the cave to be filled with undead. Fighting their way through the group come to the ruined remains of a pirate hideout. Finding the leader, a Death Knight, the maids defeat the undead. The pirates' treasure is believed to be in their ship which is submerged in the hidden port. After draining the water, by blocking the waterway and forcing the water to the entrance, the wreck is found. However before they begin their investigation, a Giant Mollusk attacks them. After defeating it the group retrieve the ship's cargo and return to Nazarick.[1]

Some months after the establishment of the Sorcerer Kingdom, experiments in [Gate] use resumed at the petition of Shalltear who wanted to test the teleportation traps on her floors. Though Albedo and Demiurge believed it was risky due to their lack of understanding on how the Cracks affected [Gate] travel, both Momonga and the protagonist supported the idea as the inability of teleportation needed to be addressed in the New World. Under the same conditions as the when first experiments were conducted, Shalltear attempted to connect a [Gate] from Nazarick on the 2nd Floor to the mine quarry. Instead the Floor Guardian unexpectedly connected to the island once more. After closing and re-opening the [Gate] a few times, the group were able to confirm that they had a stable route to the island.

It opened many possibilities for the Sorcerer Kingdom, as the island was perfect to act as a base and evacuation point due to its isolate location. Not only that it would allow their organization to conduct their operation without scrutiny from ports like the Re-Estize Kingdom and Roble Holy Kingdom. Momonga though unable to pinpoint the exact location of the island was able to divine its general direction. The Overlord wanted to use the island as a bridgehead to further exploration of the New World, while Demiurge hoped to use the new area to acquire marine resources and spearhead conquest of the seas.

While there were still uncertain where the island was located, Momonga moved a plan forward to send a scouting party. While it had yet to be confirmed the island was the same one their forces had visited before, the number of personnel they could send to explore it was limited. Aura Bella Fiora and Mare Bello Fiore were deemed the most qualified due to their forestry experience which would be useful in the terrain. However they lacked waterside combat experience unlike the Pleiades who had explored the island before but were all out on missions, save for Entoma Vasilissa Zeta. Cocytus though reminded everyone that they could draw on resources from the Lizardmen Alliance, as the lizardmen were creatures who inhabited an aquatic environment. The idea was accepted and the dark elf twins were assigned with the protagonist and Slimeko to head to the Great Lake to receive some aquatic training in their swimsuits with the lizardmen.

After training with Zaryusu Shasha, the traveler requested to be allowed to join the scouting party to sate his curiosity. His request was permitted by Momonga who agreed that the demi-humans should have a stake in the island. The inclusion of the lizardmen opened more possibilities of allowing the lizardmen to colonize the island and perhaps build an infrastructure there for Nazarick once the island was secured.[2]

The survey team now equipped with swimsuits and water training were sent out to the island. Going by the members of the previous survey team, the team combed the beach for any traces of new visitors. Along the way, Zaryusu made some observations that the island could not be in a lake due to the size of the waves. Entoma Vasilissa Zeta having used her insect summons to scouts out what was beyond the island found nothing but water and fog leaving the exact location of the island still a mystery. Zaryusu collected many samples of various crab monsters which he believed were edible for lizardmen consumption. When they moved unto the forest the only creatures they face with resistance were slimes. At the reef Zaryusu noted the vast amount of aquatic life that used it as a feeding ground.

Reports of their progress were sent to Momonga who was excited at the potential use of the island. The survey team eventually reached the cave containing the wreck pirates ship. They were not the only ones as the lizardman also believed that the island could be a new source of food for his people.

While examining the wreck, Slimeko accidentally disturbed it and caused some of the rotten wood to crumble. The disturbance caused the mud beneath the ship to loosen, releasing the remaining undead crew that had been trapped beneath it. Once the undead were cleared away, the team returned to the beach where they found Momonga, Albedo and Victim to be waiting to congratulate them. Momonga also hearing Zaryusu proposal to build a fishery on the island approved it, as the project could be supplement into the introduced plans to turn the island into a beachhead to expand the Sorcerer Kingdom.[3]

Despite the island being technically outside Nazarick and should fall under the jurisdiction of external investigations led by Demiurge, due to the [Gate] to the island being located in the interior of Nazarick, the island and its operations are technically under the purview of internal affairs which is handled by Albedo.

Later the duties of constructing infrastructure on the island was designated to the newly inducted Princess Renner Theiere Chardelon Ryle Vaiself. Under her guidance, she instructed the lizardman to expand the homes for the workers and the construction of a proper harbor at the reefs. The local monster population in the forest was put under control, though a total culling was forbidden by Albedo in order to preserve the ecology of the island. The island soon became a base of operation for Nazarick's search units who were sent out on vessels to explore beyond the fog surrounding the island.

Once the fog was penetrated, it was deemed that the solitary island where Nazarick had settled was in fact part of a larger island chain, situated near the coast of a continent. Beyond the island it was discovered that there were Chaos Beasts infesting some of the other islands. After careful investigation by the search units, the source of the Chaos Beasts were determined to be from a specific island. Due to the large numbers, it was believed by Nazarick's intelligence that the monsters either originated from a cave containing a Crack underground or that the Chaos Beasts were attracted to the location due to a large settlement of powerful beings. However it turned out to be the former, after Albedo led a re-investigation team to verify if the islands had any intelligent life.

Despite the lack of result in finding intelligent life, Albedo was able to gleam some new information on the behavior of Chaos Beasts. In addition she planned to install a military force on the new island to cull the excess Chaos Beast population. Her plan also, after the subjugation of the Three Kingdoms, Albedo intended to propose to Momonga the creation of a unit to expand the search of the neighboring island as well as the nearby continent to not only expand the Sorcerer Kingdom, but also to seek out any possible Supreme Beings. Though Albedo's intentions to seek the Supreme Beings were not to just locate them, but to eliminate them.[4]

By the time of an investigation of an illegal gambling den in the Re-Estize Kingdom was being conducted by the Sorcerer Kingdom, it was reported that the island was still being managed by Renner.[5]

The island was once again visited by Albedo, seeking Renner's assistance in teaching Lupusregina Beta and CZ2128 Delta on etiquette of nobility to help them infiltrate an aristocrat part. Renner was walking with Climb on the beach when the Overseer Guardian arrived about to take a break, but the former princess agreed to lend her help in the endeavor, departing the island, leaving Climb in charge in her absence. When Renner returned, and the mission of the two Pleiades was over, Albedo came again to personally thank the imp who gifted her subordinate a new fashionable dress that she hand-made.[6]


An isolated island with a large forest area situated inland. The outer circumference of the island is almost all sandy beaches, except for some reef areas.

Based on the logbook of the pirates discovered by the Pleiades, the pirates had stopped at a port town of the Re-Estize Kingdom, indicating that the island may be located in either the sea west to the Kingdom or in the Rhynd Sea at the north.

Though, according to the protagonist, the waters around the island have a concentration of salt, which is inconsistent with what he was told about the open sea in the New World, as it was said that the open bodies of water were actually made up of fresh water. This causes him to believe that the island is actually located in a saltwater lake somewhere in the continent, or perhaps in a new one.

However, it was found out that when summons were sent out from the island, only water and fog was seen in all directions with no land in sight. The fog is assumed to be unnatural as it does not appear to dissipate, similar to the fog in the Katze Plains. Though later on it was determined that the fog has no harmful properties and seems to only block out visibility around the island. Hence it was assumed to be a unique phenomena to the island.

While its possible that the island could still be inland, and that the shore was much further than anticipated, the traveler Zaryusu pointed out that the waves at the beach are much greater compared to a lake. Another theory of the island is that it is perhaps a lagoon that is connected to the sea which could explain the presence of the ocean going pirate ship. If pirates made the island their stronghold it would be highly indicative that a nearby town was located somewhere not far from the island to resupply.

Due to the various inconsistencies of the topography and knowledge from the New World and Ashurbanipal two theories of the island have emerged:

  • It is an island located in a large salt water lake connected to the fresh water sea by a water route.
  • It is actually an island located in the sea where the water is actually saltwater. And the freshwater seas bordering the current nearby nations of the Sorcerer Kingdom are actually an anomaly and not the current norm for the rest of the world as originally thought.

Eventually after the fog was penetrated it was deemed that the latter theory may hold credence as Nazarick's exploration unit discovered that the island was part of an archipelago.



A dense canopy located in the center of the island. A well is also located there, where the former inhabitants drew fresh water. A road once existed, but over the years the grass grew over it, covering the path completely.


Reef (Mass for the Dead)

Located away from the sandy beaches, it contains a lot of rocks and the terrain is ideal for creatures like crabs and slimes to hide. Later the rocky area was converted into a natural harbor.


Pleiades Swimsuits

Along the reef, there is a cave-like side hole in the back of a cove. It acts as the inland entrance to a hidden pirate hideout. The pirates developed a crafty method to guard the door to their hideout. Taking advantage that the inland entrance of the base was a burrow of a giant crab and the fact that it blocked the entrance during the day, it was the perfect defense. Since it was nocturnal, all the pirates had to do was schedule a time of when the crab was out at night and enter. Going deeper were several burrows of smaller crabs, where there was a second door leading to the hideout.

Pirate Hideout[]

The main sanctuary of a crew of pirates. It could be accessed through a cave in a cove on the island.[7] After passing the crab's domain, a second wall hid the main part of the pirate's base. There wall was actually a door which could be activated through a mechanism. On the other side was a hidden pool that connected to the sea and where the pirates had docked their ship.

Known Inhabitants[]

The island was home to a crew of pirates, but also contained some fauna like crabs and green slimes. Due to the negative emotions of the dead pirates, they eventually became undead such as skeletons, skeleton warriors, and even the leader becoming a Death Knight.

After the Sorcerer Kingdom discovered it and annexed it, a large number of lizardmen from the Great Lake immigrated to the island, with interest in establishing fish farms in the area.


  • Scenes from the island were later reused by the game developers in a later special event.[8]
  • The island served as the setting for the Obamas 4th Anniversary.[9]