Treasure Mining Area

Treasure Mining Area (財宝採掘領域) is a game event in Mass for the Dead that was released on October 11, 2019 to October 21, 2019.

Background
A landslide occurred at a mine occupied by Nazarick. An unknown region had spread inside the crack caused by the impact. Knowing the possibility of rare ore, such as "Prismatic Crystal," Demiurge and the others seek to challenge and control this new area.

Incident
At the Round Table Room, Demiurge gives his report he received from Abyss Demon that prismatic crystals have been discovered in the mine. The substance is considered a rare commodity to Momonga, as it can raise the limit value of leveled down NPCs. If they were to claim the mineral, the Great Tomb of Nazarick’s defenses would increase. However there is a slight problem concerning the discovery. While the freak landslide opened up a new section of the mine they have yet to find the source of the minerals in the new cave system. In addition, there is the possibility there are hostile existences hiding in the new area. To do a proper investigation they would not only have to send a team, but use people with high combat abilities. To avoid depleting Nazarick’s defenses, Momonga permits Demiurge to use agents outside of Nazarick for this mission. Among those that will be assigned are Sebas Tian, Solution Epsilon, and the protagonist.

The Floor Guardian meets his team at the rendezvous. While he notes that Solution Epsilon in her Soi persona is dressed as an adventurer, he finds Sebas Tian's disguise as Sebas to be unusual. The butler states that his clothes allow him to blend in as a refugee and laborer in E-Rantel, besides his ordinary wear would attract took much attention if he worked with the protagonist. The demon sees the logic in that, though he warns the butler not to get too attached to his surroundings or the humans. Though the comment goes unsaid that the demon doubts Sebas Tian's loyalty to Nazarick, he quickly apologizes and corrects himself stating he was merely looking out for his colleague. The butler takes no offense and promises to avoid his habits in interfering with the orders from Momonga. Now that the tension in the air is gone, Demiurge then leads the group to the entrance of the mine, where they find a bunch skeletons decorated at the front. When Soi comments on the atmosphere of the mine, Demiurge explains that the skeletons are a remnant of when Nazarick encountered adventurers. To fool them they had to disguise the mine into a dungeon and installed a 'boss'. That boss, Abyss Demon, arrives to greet his fellows. Slimeko who recognizes the demon, is glad to see he is alright, which the demon proudly boasts that the adventurers couldn't do a thing to him. Though Demiurge comments to the others that ever since Abyss Demon's experience with the adventurers he has been mentally traumatized. Though he physically recovered, the near death experience shook his confidence and thus he has been repeatedly proclaiming that he is immortal to nurse his pride. Now that everyone has gathered, Demiurge explains why the are at the mine, to confirm the source of the prismatic crystals and to judge the degree of threats in the new area. Abyss Demon will serve as their guide to the deepest part in hopes of locating and securing the ore.

Inside the mine, several summons are hard at work in extracting ores. Sebas Tian is impressed with the operation and its efficiency. Abyss Demon thanks the butler for the compliment, he also warns the group that due to the Negative Energy accumulating, undead have been naturally spawning in the caves. In addition, several demi-humans species like Stone Eaters have been seen searching for good quality ores. Nazarick has been continuing to dispose of them on a regular basis, thanks to the efforts of Entoma Vasilissa Zeta.

Going deeper into the mine, Slimeko notices that the summons are not mining the labyrinth part of the mines. Abyss Demon states that the are is being preserved in case it has to be reused as a countermeasure against intruders. Soi passing by a drawn magic circle inquires it purpose, making Slimeko feel nostalgic that it was a decoration to give the cover story of how the mine was a base for a group of summoners that summoned a powerful demon that killed them. It was an amazing performance by Abyss Demon that allowed Nazarick to succeed in claiming the mine. Slimeko even does an imitation of one of the demon's quotes much to his embarrassment. Before they can continue to reminiscence on the past, the group detect undead in the vicinity and decide to deal with them.

The group finally come before the double doors leading where the crack to the newly discovered mine section is located. Demiurge questions Abyss Demon on the door's security, which the summon states that his orders were followed to the letter. The doors have not been breached and the space isolation effect is impenetrable that even spirits would have trouble breaking through. Demiurge is satisfied as this indicates that no enemy strong enough exists on the other side to break the doors. However since the doors have sealed the section of the mine, the negative energy is accumulating and perhaps will least to an infestation of undead. To prevent this the doors are fully opened and on the other side is full of Skeletons and a single Death Knight.

With the undead eliminated for the time being, Demiurge sent a Shadow Demon to survey the crack of the mine. It reports back to state that the new fissure contains a cave system with a hierarchical structure and contains many creatures within. However it is indicated that he deeper one goes the stronger the enemies are. Demiurge cautions everyone to be prepared. He then orders Abyss Demon to stand guard at the entrance of the fissure until the investigative team returns.

In the new cave area, Sebas Tian comments that the atmosphere is quite different from the existing cave system. Solution agrees noticing that there are quite a few enemies in this location. Demiurge takes a sample of rock from a wall and determines that it is rich in rare ore. Strangely the enemy's strength in this part of the mines is proportional to ore rarity. While it cannot be concluded as why this is so, but when they kill an indigenous monster, they find it to be full of prismatic crystal. The contents are of good quality and appears to explain the cause of the power of several creatures in the area.

The party continues to traverse deeper into the caves, though Solution begins to notice how eerily quiet it has become and finds that the scattering of bones across the cave floor to be disturbing. In addition, the butler finds it strange that the remains of various creatures have increased while the ores are disappearing. So far there is no sign of any living thing before them, though something is stalking them from behind. The group collectively agree to withdraw and dispatch the entity behind them, reasoning that the lack of crystals are due to the creature behind them having eaten all the high quality ores. They opt to claim the finest gems for their master.

Aftermath
Back in Nazarick, Demiurge and the team present their survey results to Momonga. Momonga is thrilled at the results as the ores they have brought are of the highest quality. As for the new areas of the mine, not all have been surveyed, which is why Demiurge continues to send more investigation parties to remedy this. Though with this new territory open to them, Momonga believes that Demiurge will have more responsibilities in controlling the new area. Demuirge has taken care of that and recommends Abyss Demon to supervise the new area. In effect, Abyss Demon is promoted to an Area Guardian.