Magical Girl and the King of Magic

Magical Girl and the King of Magic (魔法少女と魔導の王) is a collaboration game event in Mass for the Dead with characters from Overlord and Magical Girl Lyrical Nanoha. It was released on November 15, 2021 to December 15, 2021. The event was re-released on November 15, 2022 to December 15, 2022.

Background
To be swallowed by the sudden appearance of a crack to a different world that they have never seen. The story of a new encounter and farewell begins at the Great Tomb of Nazarick, where the undead kings and demons live. Magical Girl Lyrical Nanoha Detonation collaboration begins.

Incident
One early morning on Earth in Uminari City in Japan, Fate Testarossa and Hayate Yagami land from the sky at a park to investigate an alert on an anomaly. Though the area is devoid of activity and abnormality. Chrono Harlaown communicating the the two girls via remote from base states that there should be some sort of reaction just 150 meters from them and that the phenomenon may just not be visible. Hayate is curious to know what kind of anomaly they are dealing with but Chrono and those with him don't know as it is unidentified, only stating that it is "a minute space-time distortion that resembles a dimensional earthquake". If left alone it may be cause a serious disaster. Until the containment team arrives to quarantine the area, Chrono orders the two to monitor their position. Supporting the two from afar is Nanoha Takamachi but Fate is worried of her friend's participation as the former has not recovered yet. Despite Nanoha stating that she is fine, her colleagues suggest it is still not wise for her to be overexerting herself.

They get an alert from Amy Limietta that the reaction they detected is now moving...straight towards Fate and Hayate. A Crack manifests in front of the two girls, expanding itself pulling them into a vacuum. Fate summons Bardiche and tries to anchor herself to the ground catching Hayte from being sucked in. The Crack does not let up and increases its pressure to absorb them. To Fate's shock the anomaly even begins sucking her magical energy. Nanoha comes from the air intent on rescuing the two, despite the warning of Fate and Hayate. Flying head first towards the Crack, Nanoha attempts to use Raising Heart but the Cracks succeeds in pulling all three girls in before it vanishes. Chrono and Amy on the other end of the line realize their space-time distortion has vanished. Chrono even suspects that the phenomenon was targeting those three and immediately orders Amy to contact headquarters and the Ursula in order to launch an investigation of where the trio may have gone to.

While the disappearance of the three magical girl caused turmoil for the Tokyo branch of the Time-Space Administrative Bureau led by Chrono, elsewhere taking place in the Great Tomb of Nazarick, Momonga and Demiurge are preparing for a regular summoning experiment in the Throne Room. As they work Momonga is also given a report by Demiurge. It seems that the damages by Chaos Beasts are increasing in the Baharuth Empire. Due to a phenomenon, sporadic hordes of Chaos Beasts are arriving from the central part of the continent and migrating into the territory of the Empire. The information comes as a surprise to Momonga who has been focusing all his attention on E-Rantel since it is the center of all his field operations. Demiurge reports that Nazarick has not been able to deal with the hordes and so the damages to various part of the Empire is increasing rapidly. This is odd to Momonga as he heard that during the early days of the Incident caused by the Cracks, the Empire and the Slane Theocracy were quick to deal with the threats and established a system to deal with the monsters. Unfortunately the lapse in the defenses of the Empire is from the losses of the Imperial Army caused by Jaldabaoth. Not only that the Empire lost many warriors putting down that irregular Chaos Beast horde that attacked E-Rantel. The Floor Guardian adds that the Empire sacrificed much to preserve the key point of the Tripartite Agreement but the end result has left them weak. Not only in numbers but the army now is dealing with emotional trauma from the defeat of the Four Imperial Knights by the Demon Emperor.

Given the magnitude of the problem, Demiurge suggest that the protagonist address it to the emperor so earn his favor. While cause of the Empire's military decline was the result of the schemes of the Sorcerer Kingdom, creating a powder keg that is waiting to happen, Momonga decides to leave the issue alone. At present they have not encountered an individual they cannot handle, though they still have many questions on the Chaos Beasts. The emperor is already has an obsession with the protagonist and Momonga has no wish to burden the latter.

The two are then informed by a Death Knight that the preparations for the experiment are ready. Master and subordinate are ready for the new summoning using the Chaos Stones with hopes to summoning a new batch of beings to Nazarick to help in its defense. Though noted such rituals also bring about "exceptions" such as beings from other worlds with valuable information. The experiment has Finally initiated and soon enough, Fate, Hayate and Nanoha emerge from the Crack. Once the three girls get their bearings, Raising Heart warns them that they should be careful. Nanoha, confused by her Intelligent Device's warning, soon sees what she was talking about when she notices the undead summons, as well as Momonga and Demiurge. The three are initially shocked by their surroundings and the undead. Momonga seeing them to be just children uses [Mana Essence] and note that they have considerable mana power as well as talking weapons. Feeling guilty for dragging such youngsters to his home and to prevent them from panicking and making the situation turn ugly, the Overlord approaches them in peace. The three magical girls are shocked at Momonga for being a talking skeleton, but listen to the undead who offers to open a dialogue to understand if they are suspicious and they refuse. Unexpectedly, Nanoha accepts to talk to him first, to the surprise of her comrades and Momonga. Nanoha points out to her friends that there is no harm in having a conversation. Fate, as well as Bardiche seeing that they are unable to re-establish contact with Chrono, agree. Momonga is off-put by their willingness to trust him, seeing that he underestimated the three being so young as they value the importance of information. Nanoha introduces herself to Momonga and her comrades, and provided him with information of how they arrived.

Nanoha and her friends in turn, learn from Momonga about the random summoning from different worlds through the Crack. Fate realizes that they may be on an "non-management world". This is bad considering the fact that this is an unknown world that the Time-Space Administrative Bureau is not aware of, and because of that, the rescue may take some time. Likewise, from what the girls told Momonga, He is equally intrigued by their magic, Intelligent Devices, and the Time-Space Administrative Bureau. Despite the prospects of rescue being slim, Nanoha remains optimistic so that they can find a way to return to their original world, which is something her friends can share. This comes a bit of a surprise to Momonga given the reality of the situation that the three can maintain a positive and constructive attitude. In fact, to him, it makes the three girls appear to be emotionally mature far beyond their age. He envies people that are able to compartmentalize their emotions as he feels that he's lacking that quality, Though he hopes to overcome that challenge with time.

Now that both groups have shared what they know, Momonga wishes to learn more about the girls organization and its technology that allows them to cross dimensions. In exchange, he is prepared to offer them the protection of Nazarick while they wait for their possible retrieval. The offer is accepted by Nanoha and the others, who also accept to do some work for Momonga such as fighting against some threats. On that note, Hayate inquires if such tasks be left to her and Fate, as well as Nanoha, who still needs to recover from her injury that happened sometime ago. While the request is not unreasonable, Momonga suspects that the three wish to keep Nanoha out in order hide their strongest card, but since he can't force them, he will allow it. Nanoha insists that she is still able to fight and allayed her friends fear for her condition. Reluctantly, Fate and Hayate consent to Nanoha's determination. Impressed by their bond, Momonga thanks them for their acceptance. Upon hearing from Nanoha about her magic may not be able to work properly, the Overlord directs her to his subordinates with healing magic to attend to her. After that, he sends the trio to rest in their temporary quarters.

Later the next day on the 6th Floor, the three visitors assemble for their first job. Nanoha condition has drastically improved thanks to Pestonya Shortcake Wanko's healing magic to the disbelief of her friends. Aura Bella Fiora and Mare Bello Fiore arrive and introduce themselves to the magical girls and their Intelligent Devices. Fate, who is greeting them, is initially confused by their genders since Mare is wearing a girl's outfit, and Aura is wearing a boy's outfit. But once she finds out that it's normal for them, the girl assumes that it's just a cultural thing. Aura and Mare, having heard of the Administrative Bureau dealing with interdimensional traveling, have given thoughts about possibly locating their creator Bukubukuchagama. But they in turn, focus back on their charges to prepare them for today's task. They are soon joined by CZ2128 Delta, who Aura then introduces her to the magical girls. The three magical girls and their Intelligent Devices give the Pleiades member a warm welcome, but they are met by a silent response which Aura explains that is due to CZ's personality. For the trio's first mission, Aura directs them to eliminate the Chaos Beasts on the floor.

During the culling of the Chaos Beasts, Fate, Nanoha and Hayate attack and destroy the Chaos Beasts from the air using attacks such as Axel Shooter, Photon Lancer, and Claíomh Solais. The synchronicity and magical attacks impress the members of Nazarick, making them realize that Momonga was right to be cautious of them. Even CZ breaks her stoic attitude to acknowledge the hard work of the three girls. The Automaton takes a liking to Nanoha, especially due to her cuteness and presents her a One-Yen Sticker. The gift is a surprise by Nanoha, though her comrades, Hayate and Fate, find it amusing and wonder if the samething happened if Zafira, Vita, Reinforce Zwei, Alph, Arisa Bunnings, Suzuka Tsukimura, Yuuno Scrya, or Stella Irvine were present.

Watching the peaceful atmosphere from afar in the Round Table Room are Albedo, Momonga and Demiurge. The three are pleased with the results of the battle and that Aura, Mare and CZ have diminished the alertness of their guests. Both Albedo and Demiurge think that Momonga's motion is to befriend the visitors so it would make them easier to control rather than using torture. Of course, Momonga never had any nefarious intentions for the visitors, as he truly wanted to befriend them and privately laments that many of his subordinates have such a low opinions on humans. Plus, an interaction with the trio would be beneficial for Aura and Mare, since is good for their emotional development. Still, the abilities of the guests requires them to remain vigilant. According to Cocytus, who reviewed the videos of their fight, Fate and Hayate's mobility did well in short and medium ranged battles, but Nanoha possess destructive capabilities at long range. Such power is explained to them through a Unison Device. The trio's power is concerning but Momonga is more troubled by the Time-Space Administrative Bureau, since it is an armed military force capable of crossing to different worlds. Albedo informs her master that from what she gathered, the Administrative Bureau maintains a policy to not interfere with the world that lack the ability to cross dimensions. On that note, Momonga believes it would be prudent to move some of the World Items to the 8th Floor Hierarchy and give it to Rubedo. But so far, there is no hostility between them and the Administrative Bureau, so the best option would be to establish a friendly relationship. For the girls, Momonga is interested in seeing them perform in aerial combat. The idea is agreed by Albedo and Demiurge who make plans to prepare the Pleiades to escort them, as well as interacting with the guests outside using magical flying gear. There are some thoughts of concern to Nanoha's condition, but prioritizes to measure the trio's combat ability and learn as much about their Intelligent Devices.

In the air near the Azerlisia Mountains, Nanoha, Fate and Hayate are flying marveling at the natural scenery commenting that the clear air data would be useful for Amitie_Florian for planetary regeneration for the planet Eltria. Whilst the Intelligent Devices record the data, Nanoha is curious about the native life outside the dungeon thinking that there should be many people. CZ, flying beside her, answers her question by telling her that there are indeed other nations, but their development is not at the level of environmental destruction. Also she adds that Nazarick has few humans within its hallowed halls. Nanoha relizes that there are other humanoid creatures similar to humans such Automatons and Dark Elves. CZ warns the girl that some people in Nazarick detest humans and should be careful, especially with their escort Narberal Gamma. Nearby, Narberal states that it is not a problem, but Yuri Alpha watching with them notices that Narberal is putting on a face like the normally stoic CZ, and the presence of the humans is truly disgusting to her. Yuri, ignoring her sister's discontent, advises the magical girls to come to her if they have any problems. So far, the trio find that they are enjoying their time in Nazarick, with the luxurious room, food, and medical treatment. Right now, they only wish they can give them something for all the hospitality they have been given.

Yuri is pleased to hear that from her guests and then informs the girls of their primary mission: to eliminate flying Chaos Beasts in the vicinity. Since they are troublesome foes, the maid asks the girls not to overdo themselves. Raising Heart reports that unknowns are approaching them in the air. They turn out to be Chaos Beasts shadowing a Giant Flying Chaos Beast. The magical girls and maids then take off to combat, to eliminate the minor Chaos Beasts. The boss of the monsters, seeing its minions effortlessly killed, attempts to flee but the magical girl give chase and destroy it. With the monsters deaths, the party then collect the Chaos Stones from the dead Chaos Beasts.

Nanoha, who came from the air, then notices that there are injured people below them and ask the Pleiades who they are. Yuri, who is taking a look at the injured people, tells the girl that they are most likely workers from the Empire seeking to hunt Chaos Beasts and may have gotten into a scuffle with them. Since the Empire is declining, the nation must rely on the strength of the workers rather than its own military. Nanoha finds it a pity that the people of the Empire fight so hard, though Yuri tells her that the state of the Empire is only temporary and that only soldiers and workers will be affected. Plus, the leader of the Empire is more than capable of replenishing his army in due time, and claims that Nazarick has not yet revealed its existence to the world and thus remains neutral to the domestic affairs of the other countries. Nanoha obviously has more questions, but Fate eases her to hold her questions for the time being. The group then decides to return to Nazarick.

At the Round Table, after receiving the report of the battle Momonga who had been viewing it from the Mirror of Remote Viewing found the sight to beyond his imagination. Albedo admits that the aerial speed displayed by the girls were difficult to follow. Momonga believes that it may be troublesome if their guests may try to escape without additional support. He also notes that Nanoha will be persuaded to be kept in Nazarick, under the pretense of rest and recuperation. While he keeps her busy, he directs Albedo to find a way to get as much useful information from the other girls, starting with Fate who will be sent out into the field alone on a mission.

The next day, in the skies above the mountains, Fate was flying with Narberal and CZ to deal with more Chaos Beasts in the area. The three are in a awkward silence as they travel, so Fate thinks that she should start a conversation by asking Narberal about her specialization in lighting magic. When she gets a short response that seemingly ends the conversation, Fate worries she may have offended the maid, but CZ quickly explains that her sister just prefers brisk answers and encourages her to continue the dialogue. The topic then draws towards Fate, asking more about Momonga, who she believes that despite his fearsome appearance, is actually a really kind person as he welcomed her friends into his dwelling. Touched by her words, Narberal, in a rare act of kindness, thanks the girl for praising her master. The maids then add that Momonga is extremely important to them as he was the only Supreme Being to remain with them until the end. Upon hearing this, Fate is confused by the unfamiliar terms and both maids restrain themselves from adding anything else. To distract Fate, Narberal then directs her attention to their approaching destination on the surface of the ground.

There the three women then defeat some Chaos Beasts with ease. CZ, though senses that Narberal and Fate have become depressed, Narberal being sadden about thinking about her creator, while Fate felt guilty for bringing up the subject. Narberal makes an effort to let Fate know that she should not feel bad for dredging up sad memories, as it should not worry her. And while she does feel some longing to see her creator, she treasures the memory just as much. Fate can relate to this with her relationship with her friends, Hayate and Alph. CZ watches and is amazed that Narberal is quite favorable towards the magical girl in contrast with her usually demeanor. The group then decided to return to the dungeon with the mission over.

Elsewhere at the same time, Hayate Yagami is flying with Yuri Alpha, Entoma Vasilissa Zeta and Lupusregina Beta. The four women are having a casual chat while eating snacks. When Entoma begins to describe her favorite snacks, Yuri warns Hayate to divert her ears as her younger sister's taste is a bit lively. The interplay between the maids reminds Hayate of her platonic bond she has with Rein and Vita who she sees as her younger sisters which Yuri relates to with her own sisters. After chatting the maids and magical girl then land to take care of some Chaos Beasts. Though the job is finished Hayate is absentmindedly thinking about her little sister Rein. Her teammates try to encourage Hayate to have fun and that the day would come that she would see her family again. Their words cheer Hayate up who appreciates the maids for their support. They group is soon joined by Fate's group who together return back to Nazarick.

Meanwhile in the Guest Room, Demiurge is finishing up an interview with Nanoha and Raising Heart on all the technology and science from their world. As per Nanoha's request she is later given an audience with Momonga. Understanding that Nanoha cannot help but get the image of those suffering people she saw outside of Nazarick and Fate reminding her not to overexert herself. Sensing his partner is troubled Raising Heart tries to console her that it will be alright. Due to it being sudden, the meeting takes place in the Throne Room where Momonga is conducting an experiment with the Chaos Beasts along with Albedo decked out in her Hermes Trismegistus. Momonga is informed of Nanoha's wish to meet with him after Albedo tells him of a report from Shadow Demon that was spying on their guest. He allows Nanoha to enter the chamber and before they speak asks her to help him subjugate the annoying Chaos Beasts. Once the beasts are destroyed both [arties compliment each others' abilities in the battle. They then get on the main subject of the meeting, which Momonga guesses correctly that it concerns the Empire. The nation's strength is declining due to the increasing Chaos Beasts roaming its territory. Due to the destruction Nanoha wants to know if there is any way that Nazarick can help even though Momonga wishes to keep its existence a secret. Momonga understand her concerns as the Empire is indeed in trouble, though his main concerns are concentrated on upsetting the Time-Space Administrative Bureau. If anything should happen to Nanoha and her friends when they go out on a humanitarian mission alone, the Time-Space Administrative Bureau may blame Nazarick even if they give them evidence stating otherwise. Momonga is not unsympathetic to Nanoha, as she very much reminds him of someone who was very selfless. In fact he would very much like to support her way of thinking, but since he is an undead he cannot fully express it. Nanoha understands and promises that she will return safely once she aids the people outside Nazarick. Pleased at her idealism, Momonga gives his consent for her to go out of Nazraick and do what she can for the Empire. Albedo then bring Fate and Hayate who have been informed of Nanoha's intentions to go out to save others, also wish to aid their friend in the next mission.

Aftermath
On a grassy path, a little boy and girl are seen fleeing for the lives from a group of Chaos Beasts. Seeing them gaining on their heels the boy decides to delay them to allow his sister to escape. Despite her protests the boy takes a rock to throw at the monsters and charges at them. Before the monsters can touch him, they instantly vanished. The monsters gone, the boy's sister thinks that her brother is responsible for defeating them. Unknown to the pair, Nanoha, Fate and Hayate are flying above, having used their powers to kill the Chaos Beasts from the air. Their work is complimented by the protagonist, Surako, and Soi flying next to them. To take care of the children, Soi is sent down to rescue the pair. The magical girls it appears have been actively hunting down Chaos Beasts throughout the Empire, allowing the protagonist and his friends to take credit for the victories to bolster their reputation as adventurers. Everything is progressing well, as soon their efforts will become redundant as the Empire will be finished replenishing its strength by organizing adventurers and workers into an army using rewards to entice them to enlist. Nanoha feels proud at the good she and Nazarick have done, when a communication link sounds from her. The voice on the other end is Chrono who is relieved to know Nanoha, Fate and Hayate are safe. Also on the other end are others such as Vita, Levi, Rein, Signum and Zafira from the Time-Space Administrative Bureau.

Regrouping back to Nazarick in the Round Table Room, Nanoha tells Momonga of her report to the Time-Space Administrative Bureau. The Time-Space Administrative Bureau has located the world Nanoha and her friends are on and are sending a ship, the Ursula to retrieve them. Though according to Fate there seems to be a special circumstance as the surrounding dimensional space around the world is distorted so the Ursula cannot come directly. The best the vessel can do is barely standby to the world. Momonga understanding this means that the trio have a limited window of time to be rescued as the world's space is hard to navigate a dimensional transfer. Demiurge hypothesizes that the distortion may be due to the Cracks. In his suggestion to create a stable way to get the trio transferred out of their world, they should attack the Crack as it worked previously in other cases to establish a route to another world. Ursula would then just need to be ready to detect the coordinates and pull the trio to them. For this to work Momonga offers full cooperation and suggests that the use the Crack in the Great Forest of Tob.

Demiurge immediately put forth his master's plan in motion. Mare helped to ensure that the damage to the forest would be minimal. Members of the Pleiades such as Entoma, Lupusregina and Narberal take care of the Chaos Beasts and supported by Aura and Mare. Yuri and CZ with Nanoha and her friends then directs the girls to be ready. Momonga via a [Message] thanks the girls for their help, stating their efforts made a difference for the Empire. Not only that the information they provided was invaluable and for that Momonga expresses his deepest thanks. The members of Nazarick then give their goodbyes to the three girls before they activate their attacks to disruot the Crack. The Crack only receiving the attacks shudders before releasing a bright light causing the magical girls to vanish.

Back at the Round Table, Momonga wonders if the Ursula was able to retrieve their guests. Demiurge is a bit disappointed that they were not able to get more information directly from the Time-Space Administrative Bureau directly. However it seems now unlikely given the disposition of the organization to not interfere with worlds that do not possess the ability to travel to other worlds. Albedo mused that they could have used Nanoha as a hostage, but Momonga states that it was probably for the best as they should not take the risk and provoke the Administrative Bureau. So they should appreciate what they learned from Raising Heart and Bardiche. Plus the three girls helped them in gaining the trust of the Baharuth Emperor's sovereign for the protagonist. As for the humans that were saved in the whole endeavor, that was just a complimentary benefit. Momonga though he knows that the lives of humans were not much of a big deal, it does cause his mind to linger to Touch Me and his ideals and how Nanoha reminds him of his old friend. When his aides ask him if anything is wrong, Momonga clears him mind stating that it was nothing.

Back on Earth, Nanoha, Fate and Hayate fly back in Uminari City. Their friends are happy that they have safely returned without any issue. Though there was some concerns over the world that they visited as their instruments showed that the laws of physics seems to deviate from normal parameters. Aside from that the three are in good health and that is all that matters. Their families are relieved and wish to see them soon as they have come back. Fate and Hayate obliged to do that and head to reunite with their families. Nanoha stays for a while thinking back on her conversation with Momonga, seeing that her benefactor was sad when he mentioned his friend and how important that friend was. Reality comes back to her as her friends call for her and she rushes to catch up promising to herself to get stronger for the sake of her friends.