Queen War -YBI Plan-

Princess War -YBI Plan- (正妃戦争-YBI計画-) is a game event that occurred in Mass for the Dead. It was released on June 3, 2020 to June 15, 2020.

Background
The Trial of Love that Shalltear Blood Fallen has divined as a secret test that Momonga wishes to test his two potential suitors reaches Albedo who has been devising her own plan to challenge the draw outcome of the Princess War. While Shalltear's method to gain Momonga's love failed, Albedo is determined to succeed. To assist her she solicits the aid of the protagonist and Slimeko at Ashurbanipal. Seeing her in their sanctuary, the two suspect that Albedo wishes to complete the Trial Of Love which is now mute as Momonga has declared it to have served its purpose. Though Albedo says otherwise and wants to partake in it using her own plan which has been titled as "YBI Plan".

Incident
Momonga who has been reading a report concerning the possible existence of players in the New World. His thoughts are interrupted when a maid on duty to serve him comes into his study. Without looking up he allows her entry, occupied with the idea of giving the maids holidays. It is only when the maid invites herself to him does he realize who the maid is. Albedo now wearing a maid outfit much to Momonga's shock. Confused as why the Overseer Guardian is in a maid uniform, Albedo explains that he had given her permission a few days when he and her were discussing the frequency of missions outside of Nazarick. Besides Solution Epsilon, the protagonist and others the two found that they were facing a shortage of help as there were some tasks that the general maids cannot do on their own. That being, handling security and cleaning work on the 10th Floor which has become extremely dangerous. Usually the Pleiades are assigned to such tasks, but Momonga does not wish to overwork them and wants to find an alternative solution to alleviate the woes of the 10th Floor. When Albedo states that she has an idea, Momonga accepts it without question, trusting her to handle the details. The result of his hasty decision now has caught up to him in the present and he finds that Albedo took it upon herself to serve as a maid to handle the 10th Floor upkeep. She makes two reasons for her presence in substituting as a maid. One is to experience the daily maid operations and the second to review the work efficiency of the general maids and Pleiades. Her reasoning convinces Momonga, especially when she suggest in providing an opportunity to reward the dedicated maids.

Albedo then began working as a maid in Nazarick as well as doing her duties as an Overseer Guardian. In the Round Table Room, Albedo is being instructed by Yuri Alpha and Lupusregina Beta on the proper way to make tea and drink it. Albedo assures them while as a maid she will be considered their junior.

In the Lemegeton, Entoma Vasilissa Zeta and CZ2I28 Delta are cleaning and guarding the area. Shizu gets into a brief argument with her sister, noticing that the Arachnoid came back from the Black Capsule for a snack, scolding her for eating on the job. Entonma points out that Shizu does so as well, and points out that her cockroach is small and convenient. Albedo soon arrives and politely tells them to not fight while on duty. She compliments them on the cleanliness of the room, which the maids agree as the Lemegeton and library are among the areas that have been repaired. Shizu though wishes to clean the Throne Room, but due to circumstances of the Rift it is too volatile and dangerous. Albedo then joins the two maids in "cleaning" the Throne Room of Chaos Beasts that are scheduled to emerge from the phenomena.

Later on the 6th Floor, Albedo finds herself working with the general maids harvesting the crops in the fields. Though the Overseer Guardians read the reports of the maids' tasks, after doing them see finds that they are busier than believed. Foire states that the workload isn't too bad as they still have a lot of free time compared to Albedo. Albedo offers to add some "leisure time" to the schedules so that they do not overwork themselves which the maid takes into consideration. Aura Bella Fiora comes around and notes that Albedo really looks like a maid now. Narberal Gamma is appreciative towards her superior in assisting the maids. The dark elf is curious that Albedo is now getting familiar with the maids, and she is proven right as Albedo is secretly using this opportunity to further her own agenda. Being a maid gives her the perfect bride training program to serve Momonga. Narberal and Aura plan to head to the Rift on the 6th Floor to quell the Chaos Beasts which Albedo invites herself. Shalltear Bloodfallen and her two Vampire Brides also arrive to the campaign and are shocked that the rumor of Albedo becoming a maid is true, but vampire suspects that Albedo has an ulterior motive.

Back in Momonga's study he is working at his desk, while Albedo cleans the room. At one point Albedo request two Eight-Edge Assassins on the ceiling to make room so that she may be able to clean the area. Momonga watching her finds the whole experience new but not uncomfortable. Even Sebas Tian praises her work with a passing score, making Albedo's presence among the maids and staff to be accepted. However there are some exceptions, being Shalltear.

While in the Throne Room, she slays all the Chaos Beasts that have come from the Rift. After the extermination is done, Demiurge tells her that he will handle the collection of the Chaos Stones as he knows she is eager to be somewhere else. Shalltear quickly then departs and finds her target, Albedo in the hallway of the 9th Floor. While Albedo greets her in an innocent manner, Shalltear is not fooled and demands to know what she is up to. Albedo coyly states that she has no idea what the Floor Guardian is talking about and excuses herself. Once the Overseer Guardians departs, Solution Epsilon joins Shalltear who has been observing Albedo at the latter's orders. The other maid can find nothing out of the ordinary other than Albedo being resourceful as a maid, but Shalltear insists that something is going on. Solution shares her concern, noting how her sisters have taken an interest in Albedo since she returned to Nazarick. Shalltear suggests maybe that they are under the influence of mind control or a magic item, but the maid doesn't believe that is the case. Still knowing very little Solution promise Shalltear to get to the bottom of Albedo's plot by talking with the other Pleiades.

At the room shared by the Pleiades the Yuri, Lupusregina and Narberal welcome Solution back. The slime happily greets them and they chat, with one of the topics being Albedo's skill in being a maid. The others state that Albedo is quite competent in housework. Other than that they don't seem to find anything wrong with her abilities, though she she seems to be working her hardest while serving Momonga making Solution suspect Albedo is using the maid work as bride training.

Aftermath
To Be Added...