Blue Roses Subjugation Plan

The Mine Dungeon Project was a collaborative enterprise orchestrated by Demiurge in Mass for the Dead.

Objective
Ever since the Catastrophe, the threat of Chaos Beasts have deeply affected the human nations. A consequence of this disaster is the rising prices of ores needed for weapons and armors. The Great Tomb of Nazarick still recovering from the calamity sought to find a stable source of income to supply the funds needed to repair the dungeon. Demiurge seeking to capitalize supply and demand of the ore market located an abandoned mine and began an operation to extract ores with the intent to sell the materiel to the human nations. Unfortunately, the operation came under the danger of being exposed by adventurers led by Blue Roses seeking a new ore source for the Re-Estize Kingdom. After being informed by their spies in E-Rantel, rather than retreat and abandon their claim on the mine, Demiurge enacted a plan to turn the mine into a "dungeon of death" to make the mines unsuitable for human occupation.

Procedures
Momonga gave his support of the plan suggested by the Floor Guardian, providing the demon with a troop of Skeletons as a start. It was urged to minimize the use of resources from Nazarick and so Demiurge enlisted the aid of a few NPCs from Nazarick. The monsters that already inhabited the mines such as Hanging Spiders were subjugated by Entoma Vasilissa Zeta to be the dungeon's minions. Mare Bello Fiore changed the internal structure of the tunnels to create locations where monsters could ambush intruders in the tunnels. A fork in the mine was created to eventually separate the adventurers to further weaken them. Demiurge wished to ensure that the mine developed a worldview that would have an impact on society when word got out of the horrors within. An elaborate cover story was created, having the mine being a place where a demon summoning that went horribly wrong occurred. Abyss Demon provided the altar of which this summoning occurred and Demiurge's demons would create a demonic atmosphere. Additionally, throughout the tunnels, they planted evidence of demonic forces as work in the form of foreign summoning circles, tomes and corpses to make it convincing.

Results
Blue Roses and the adventurers they led found the bodies of the scouts and determined that the mine was inhabited by not just simple monsters. Furthermore, as they went deeper the noticed that parts of the mine was artificially constructed. The situation confused them but the adventurers went deeper until coming to a fork. The team split out with Blue Roses and the protagonist and Slimeko going through the old tunnel while the remaining adventurers went into the new tunnel. While separated Blue Roses encountered demons and Entoma which they defeated. They found the traces of summonings, a determined that unskilled summoners attempted to summon demons but they turned against them. To prevent the demons from spreading out the adventurers vowed to kill all the teams. The other adventurer team was killed, preyed upon by Imps and Slimes, leaving Blue Rose and the undercover Nazarick agents left.

They finally came to a chamber with a grotesque altar made from a human's corpse, where Abyss Demon made his appearance and claimed that he was summoned by a summoner who was decorated the altar. A fight ensued in which Lakyus seemingly defeated the demon using her famed sword. To prevent the adventurers from landing a killing blow on their comrade, Slimeko and the protagonist activated a fail-safe, triggering poison gas to flood the chamber. This forced the heroes to evacuate the mine outside for safety. The existence of the poison now made it impossible to operate a mining operation. While the adventurer team admitted they failed their mission in securing the mines, they deemed it to be a victory as they stopped the demonic infestation.

Back in Nazarick, Abyss Demon was teleported back to the dungeon where his wounds were attended by Demiurge. The plan was a success in Momonga's eyes as Nszarick secured the mine from further human intrusion under the cover it being a hazard for human activity. Thus mining operations resumed without interference. Weeks after the failed mine reclamation mission, an emissary from a foreign country, Lupusregina Beta, arrived in E-Rantel with cheap ores to sell. Thus the Re-Estize Kingdom was able to acquire the needed metal for its defenses whilst Nazarick was able to acquire a stable source of funds for its restoration.

Trivia

 * When the first adventurers came they were quickly killed and their crucified bodies were used to decorate the entrance.