Nasuverse Fate/Stay Night + Overlord Crossover Fanfiction Ideas Thread

Hey everyone,

I'm MathiasNightlord01, an author from 

The idea I have is similar to the fic Fate Revelation Online by daniel-gudman, but with a different series. Not sure if a lot of you have heard of it or not, but the series called is "Overlord", which like Sword Art Online and Fate/Stay Night is based on a Light Novel, which also has a Web Novel, Manga, and Anime Adaptation. And it seems to be a pretty good read and the anime seems pretty good so far. 

Basically its where an online DMMORPG player called Momonga, along with his Guild Headquarters/Dungeon and the Guild's Custom NPCs, on the last few minutes of the game before its shutdown are transported to a whole other world where it seems that every centuries or so (by this new worlds timeline) players from the DMMORPG that Momonga was playing (YGGDRASIL) are transported to the New World. Momonga's avatar seemingly becomes his real body and the NPC's created by Momonga and his former guild members have come to life and gained true sapience. I could go on futher but I'd typing all day just to cover it. But yeah that's the basic gist of it. 

I think this series would make a great crossover with Fate/Stay Night. And after reading the Fate Revelation Online fic, I wonder if any of you guys have any ideas on how someone could work this idea or would like to try a to write a crossover of these two series since there is exactly 1 story for this category on (A Rusty Edge by Cardinal Grief).


KING (In Land of Blind)
Staff member
me said:
I'm familiar with Overlord. I've read the first two-three LNs, but I haven't seen much of the anime.

Anyway, there's actually someone working on a cross of that with Fate right now; A Rusty Edge by Cardinal Grief. It's okay. It does the typical "Replace Protagonist A with Protagonist B" crossover, which is usually lame, but it was at least clever enough to address the fact that Overlord was set like a hundred years after FSN by making Shirou super-old.

I'll give it a little thought.

Well, if it was me, the important thing is that they're transferred to another world that runs on game logic, rather than apparently trapped in a game. Typically if it's Dimensional Shenanigans the stereotype is to blame Zelretch. I think it would be more interesting if he sent somebody (Shirou, Rin, whoever) to go investigate by flinging them into the other dimension after Momonga.

For example, one of Zelretch's wayward apprentices used a half-assed method to "find" or even "create" the game world, which he can then sacrifice to pull off a Big Spell and accomplish something. Basically, some Nasuverse magus nerd is the Demon God who will destroy the world?

You could instead approach it from the direction, "how do the cast know Momonga."

Personally, since the main character was from an Evil Guild, then Shirou played a straight-forward Paladin-type Lawful Good / Paragon character build, and challenged their Guild Headquarters, more out of the logic "well they designed their castle to withstand attacks, so it's only polite to attack it" than out of some kind of Alliance/Hoard chauvinism. Like, he would be really nice about it, and treat it like they were playing a game together, only attack when the Players were there to defend it, that sort of thing.

...Also, as a Hero, attacking a Guild of evil-type characters in a VR game is actually surprisingly useful practice for assaulting the Workshop of a magus who fell from the right path. Maybe the magic is completely different, but that feel and attitude is similar enough that it's supplemental training, not just a hobby...? Something like that maybe; he was focused on PK because it was a good way to practice battle against other people with supernatural abilities, so he actually didn't run dungeon instances that much.

Well, the point is, he attacks the guild on the night the server goes down, kind of as a way to say goodbye.

Well, the result is, someone that Momonga considers a friend gets pulled into the game as well, but all the castle NPCs absolutely definitely consider him an enemy.

That would be the best way to hit the ground running, I think; start with Shirou attacking the castle, blitzing past all the defenses because time is tight; but he bursts into the throne room with just a few seconds to spare, so instead of a fight he just chats with Momonga a bit.

Then they cross over to the other world, the rest of the NPCs burst into the room, and Momonga has to talk them down, because of course they're not going to fight in that situation.

That would set up a scenario with a lot of internal social friction, which I think would be productive.

Of course, Shirou would generally keep his last-world Magecraft a secret, while using the "game" abilities freely.

Of course, effects of UBW would still be reflected on his status screen...?

Off-hand, that's about the direction I would go for an Overlord cross.
Let me add:
I generally, I think too often crossover ideas start as "hey wouldn't it be interesting to mix two settings together", but from there, a plot isn't added to drive the action, so it's just the two casts meeting each other and shaking hands, and then the story peters out once they say, "okay, now what?"
Ok well on the e-mail I was wondering your thoughts on these ideas.

It is stated somewhere in the light novels that players from YGGDRASIL every 100-200 or so years are transported to the New World, so Shirou could in fact, arrive centuries before or possibly after Momoga/Ainz Ooal Gown.

Shirou could have a few of his own custom NPC's and even his own guild in YGGDRASIL that are either:
A ) Close allies with Ainz Ooal Gown (the guild)
B ) Are friendly rivals with them but not necessarily as enemies.

Or He could join the Ainz Ooal Gown Guild as the 42nd Supreme Being that was there with Momonga when they were transported to the New World.

As I understand it, the Ainz Ooal Gown Guild was made became most of its members couldn't enjoy the game due to being discriminated and being PK'd everyday due to choosing monstrous Heteromorphic races and were close to giving up the game because of it rather than being evil, but chose to be evil since everyone already wanted them to play the role of the villain might as well play it well (Remind you of anyone from F/S Night?). I think Shirou could sympathize with that don't you think?
The Problem with crossing over Overlord with anything is that the power levels and abilities of Nazarick and Yggdrasil is way to ridiculous. There is practically no major conflict so far in the anime because Ains and co stomp over all their enemies, besides Shalltear vs Ains. 

Having just a story about Shirou and Nazarick fighting in the godzilla threshold, either against or with each other, would likely not be very entertaining. A good writer probably can make it work though. Daniel's idea is pretty good and in character, however Shirou blitzing past the Guardians alone is unlikely because they were designed to deal with entire raiding parties of high leveled characters, unless Shirou painstakingly grinds all the way to level 100. Ains, who is pretty much the strongest Player Character, except for Touch Me, fought evenly but eventually was overcame by Shalltear until he used his OP [The Goal Of All Life Is Death] ability which allows him to instantly kill anything, even bosses. 

There are a good amount of ways you can get around this however. To Shirou using something to dungeon bypass Nazarick's floors, I have a mental image of  all the bosses having their overdone boss intros while Shirou just runs to the exit. Another idea is Shirou inheriting Touch Me's sword and shield which are some of the strongest weapons in the game. With the weapons, Shirou's actual battle skills, if post grail war, and the fact that the guardians are still all AIs and therefore likely have an exploitable attack pattern that Shirou has figured out through his constant battles with them. 

Interactions between Ains and Shirou and Shirou's reactions and actions between the, pretty much, all evil Nazarick NPCs are likely going to be the defining point for a Fate/Overlord crossover. In Overlord the major thing Ains wants to do is find other Players that were transported to the New World so he can have someone to be true friends with, that is not a subordinate or one of the New World Natives. Shirou can act as a morality chain to Ains to keep him relatively good, or at least not as bad as he gets in canon.

Also are novel spoilers okay? Because I have a story idea to add, but some of it could spoil the latter parts of the novel.
the real problem is not the Powerlevel of Nazarick (or the translation of 'MMORPG to new world' concepts) but the fact that the New World characters are 'underleveled'.

if anything Shirou could be 'Touch Me' or one who shares a lot of characteristics with said 'Player'.
while Momonga was indeed in the middle of the High Ranking Players he was mostly a true Role Player and PVE-er, so i don't get where the whole is the "Strongest PC", because in YGGDRASSIL he plainly states that he wasn't even remotely in the top 20 of 'strongest players', but i agree that he was indeed on the top 50 of the Most SKILLED Players and in the New World he is indeed one if not the Strongest Being because he is level 100 and most of that world beings (including other 'older players') seem to be level 60 at most (in WoW terms it would be like a 'starting' DK trying to play in a 'standard' starting Zone, he would be way too overleveled to get any kind of challenge).
the selling point for me would be how these 3 worlds are related (YGGDRASSIL-New World-TYPE MOON):
if the three are separate worlds and shiro comes into the New world thanks to the Kaleidoscope (the Parallel world thing, not especifically because of Zelretch, Rin or the Grail collapsing or granting his wish) then you would have to put Shirou Vs Nazarick (because most of it's inhabitants are Real Monsters fanatically devoted to a percieved 'evil overlord' to the point that they make Yanderes look and act Sane) if only to protect the poor idiots who are in a bad place at the worst moment possible.
If Shirou (Somehow) is also a Player Character (and thus a Supreme Being that may or not be a member of Nazarick) then he could be used by Momonga as a morality Chain/Pet (even if just to justify Momonga not wanting to act like a monster or let the NPC act on their 'evil alignament').

as for them battling eachother, Shirou would win (or at least have enough advantages as to not being instantly owned his own ass) because while YGGDRASSIL and New World beings still operate on 'MMORPG' Rules/Logic Shirou operates on Visual Novel Logic/Rules and thus hasn't got things like 'cooldowns' and access to 'Super Magic' Capable of creating Divine (if not World level) Items at 'will'.
but i agree that Momonga would and does have better stats, 'ready' reasources and companions.
as for [the Goal of all life is Death] being what 'defeated' Shalltear? i call BS on that, what defeated her was Momonga being experienced in PVP and knowing the Rules, because all that OP skill trully do was making the use of Death Magic (Cry of the Banshee) deal with the Einheirjar and her summoned creaturs to prevent her self-healing her exhaust her MP a couple of kills and her 'resurrection' artifact which let Momonga finally defeat her with the use of Ainz Ooal Gown Equippement and Super Magic.
plus the fact that Shalltear was more or less an Anti-Momonga NPC.
“Let’s see… Because I was at a disadvantage, because I would turn into a weakling once my MP ran out… And because you thought as much, for not saving your power, I am very grateful, Shalltear. If you had fought with discretion, the battle would not have gone nearly as well. “
“The most important aspect of PVP is how well you transmit fake information to your opponent. For example, switching your equipment in order to raise your holy resistance while acting as if it was still effective. While on the other hand, leaving your weakness, the fire attribute, untouched. Only… my predictions were slightly off. I expected you to use ?Analyze Life? and had prepared ?False Data: Life? in advance, but it ended up being a useless effort. If you ever get another chance, make sure that you clearly observe your opponent’s health. Otherwise, there will be a large disparity between devising the plan and its execution.”
“From the beginning, I too wished to end this battle in a melee.”
cue use of the Armory of Past Guildmates, pissing Shaltear beyond reasoning and finishing with Super Magic
in the end it all depends how you want to handle Shirou (as part of the 'Players' or as an 'Anomaly') wich have their restrictions, advantages and opportunities for developement.
What about a story where Shirou appears centuries Before or After Ainz/Momonga in the New World? It is mentioned that Y-Players are transported there every 100 years or so. So having him appear at a different point the New World Timeline wouldn't be so much of a stretch I would think.

As for the OP abilities of Y-Players in the New World, there have been stories where Y-Players like the Evil Deities were defeated by New World Inhabitants ( though admittedly with the help of Two Y-Players and a disguised Dragon Lord), 

Plus, there are still the Dragon Lords to consider, as its never explicitly stated exactly how powerful they actually are. They were defeated by the Eight Greed Kings but its still possible that they could match a 100 Y-Player in combat  but lose to a group of 100 level Y-Players working in tandem against them. They may appear later on in Overlord to challenge Ainz, as hinted with the appearance of the Platinum Dragon Lord and his conversation with one of his former companions among the Thirteen Heroes.
Another thing that could provide a challenge are the God-kin, descendants of previous YGGDRASSIL players that had kids with the natives and the same potential power. In volume 4 there is an interlude about them and the Slane Theocracy has 3 of them with the top-tier equipment to match.

As for drop off points, if you want any connection with canon characters you're going to drop him off at the same time as Ainz or maybe during the time of the 13 heroes, anywhen else and you'll have to make up everything but the countries from scratch from lack of information.


Well-Known Member
To tell the truth I would be much more interested in a Overlord/Fate Revelation Online crossover than a pure Overlord/FSN.

So, spoilers for Overlord, SAO and FRO itself:

Ranked Magic would be substituted by the [Thaumaturgy System], YGGDRASIL would be a SEED game with the realism settings set to [Realism? What are you talking about?] a world with innumerable Ley Lines and absurdly abundant Mana and reagents. To the point where things that would be absurdly impractical and completely unfeasible either IRL or Airncrad would be common.

Self modification with Magecraft would be relatively popular, with people doing things that would be insane IRL, like turning themselves into a Lich or a tentacled monster or a slime for example.

At the server shut down Momonga and the Great Tomb of Mazarick are transported to the New World just like canon. Where he is, like canon, absurdly overpowered due to being a fucking Lich made up of Mystic Code bones or whatever and having an absurd Circuit count due to invasive self-modification.

He would have to deal with maintaining his infrastructure (includin whatever weird requeriments his own body has) in a world with sane magic resources (analogous to Ainz having to be careful spending YGGDRASIL's currency in game mechanics only much more difficult) apart from dealing with the suddenly sentient NPCs and the politics of the New World.

In truth this would be a secret project of Rath (the company affiliated to the Japanese government from SAO's Alicization Arc) similar to the one occurring in canon, their goal is, officially, experimentation with AIs and, unknown to most, Magecraft and Soul Translator technology.

They were using YGGDRASIL's Players to create IAs(NPCs) that they later intended to dump alone in a new server (the New World) and see what happens (there are supposedly better reasons that that, but that goes beyond the scope of the story). While people where playing, the NPCs were silently watching and running the backstory parser that slowly but surely was training their IA.

So, someone was really dumb and didn't account for the possibility of people still being connected when the dump happened, so now people are trapped in their shinny experimental server. Someone from outside will probably notice, eventually, and then things will get more interesting as the outside begins interfering.

As for the other part of the experiment, that's why the New World exists. Through a similar process to the one used in canon SAO, and with the help of Magecraft, they managed to create human Souls inhabiting a Virtual Reality. Their current line of research is all about trying to give all their Artificial Souls(AS) Circuits, for now it seems to work as it does naturally IRL and somehow Kayaba's method for soul rebooting isn't working.

Yes, all species in the New World are packing human AS, part of the point of the experiment is examination of the effects that having a body hugely divergent from the human form may have in a Soul.

The New World is a server with the Realism setting set to the absolute max. It is like the last floors of FRO's SAO without the menus. Fortunately for Ainz, many of the game mechanics that canon Overlord keeps still exist but the price is Prana instead of Gold. Resurrection is possible as a Thaumaturgy spell, as that was the re-spawn mechanic in YGGDRASIL, for example.

This world, as a SEED server, has it's own Cardinal System, probably embodied like the one in the Alicization saga. Once the people running the show get a clue about how much they screwed up they will probably send someone inside to at least see what's happening. They may or may not be a previous SAO player and they may or may not be filling the Generic Hero shaped hole that exist in the otherwise generic, if subverted, RPG Overlord Storyline.

The other Players that existed in the past of the New World were in fact dumped into it at the same time that Momonga, the servers used by the new world are being accelerated like those used in SAO (althroug in this universe this is due to time Magecraft) and due to connection shenanigans and the way they loaded the data into the new server people entered the world at different points of time.

As for the Dragon Lords and their Wyld Magic I have no idea what to do with them... maybe they are a manifestation or tool of Cardinal and their Wyld Magic is accessing system commands?
Hey guys,

New thought just came to me about how to make an Overlord/Fate Series Crossover.

You know how Ranked Magic was introduced into the New World and supplanted the native Wild Magic? What if in the crossover scenario, Shriou (or possibly others) arrive and teach the native population how to use their style of magic, Thaumaturgy/Magecraft? Which is more specialized but doesn't rely solely on power levels and more upon skill? As in Fate Series a powerful Magus could be defeated by a weaker one if that individual had a way around that to kill them or a hard counter to their abilities. The same applied to NP's and Servant combat, as a weaker servant could overcome a weaker if their NP has a way around their abilities to kill their target.

With Tier/Rank Magic however, it's more rigid in structure and is mostly dependent on levels/power a person has. With Nasuverse Magecraft however, it could be made possible through unique applications of magecraft to overcome stronger opponents with skill and ingenuity rather than power. And if introduced, would throw a wrench into peoples plans since no two people practice Magecraft in the exact same way and thus you'd have to spend time trying to get around their mysteries.

The more conceptual nature of Nasuverse Magecraft, if introduced into the New World. Could completely upset the balance of power as more and more people learned to use it. Thus, leading to a potential conflict.

And if Shirou and Ainz are potential enemies in this setting, Shirou could end up being the counterbalance to Ainz by training New Worlders to use Magecraft that would throw off Ainz a bit due to the nature of it. Sure he and his followers would still be pretty freaking OP but it wouldn't always guarantee them a victory, depending on how a person decided to fight them and if their magecraft was effective against certain types of enemies.

Plus, there is also the added factor that maybe Magecraft isn't affected by YGGDRASIL skills and magic. As those skills and magic may only be most effective (and where designed to counter) other Skills and Magic from the same system. And since Nasuverse Magecraft is actually founded in systems grounded in IRL Magecraft, than that magecraft would have more metaphysical weight behind it than a system grounded in a game-world like YGGDRASIL doesn't have the same amount of "history" or "mystery" as Nasuverse Magecraft.

Hope this makes sense to you all.