When Jubstacheit von Einzbern gave you Avalon to use for your summoning, you expected to summon King Arthur Pendragon of the Round Table. What you got instead was a flamboyant man calling himself a 'Demon Lord' that would have been more suited to the Caster class rather than the Saber class. You had to smuggle him into Fuyuki yourself, with the help of Maiya Hisau to make sure he actually behaved.
With your surveillance, you managed to watch as Assassin tried to launch an attack on the Tohsaka mansion, but was apparently slain by a man wearing golden armor. You weren't able to confirm the death, because immediately after killing Assassin, the golden man fired a sword at your surveillance equipment and destroyed it.
A few nights after the incident, after Irisviel von Einzbern arrived and your group set up your base, you moved to the docks to where you had felt a Servant presence. To your surprise, the red and black Assassin that had been killed was hiding on the crane, and to your greater surprise, the Servant that had sent out a pulse of Prana to attract attention was a girl about fourteen years of age in a red dress snacking on Pokey.
Your Saber fought against the girl, who was revealed to be Lancer, for a couple minutes before Iskander the Great, the Rider, crashed into the battle and requested everyone to join him in the quest for the Grail, claiming that another Rider had already done so.
His Master, who was identified a minute later as a Waver Velvet, rode in after him on a pale horse, tiredly complaining of Iskander's methods. Kayneth El-Melloi Archibald revealed himself to be the Master of the young Lancer and started threatening to kill his student, before being brought to a halt by Waver's other Rider. While he didn't state his name like Iskander did, the black cloak and scythe pointed towards him being Death.
The golden Servant appeared, demanding obedience of everyone, and letting everyone know of his identity of Gilgamesh. Before he could get a response, however, a Servant dropped out of astral form and started attacking everyone it could.
You lost your composure when you realized that Godzilla had been summoned under the Berserker class. Everyone retreated.
Before the morning arrived, you learned that Archibald had been killed by a demon summoned by an unusually persistent Caster who seemed hell-bent on eliminating his particular Servant, causing his Lancer to be claimed by your wife. However, one of the men of your mundane contacts had found himself inside the Einzbern mansion due to the 'Tactical Genius' of the Servant of Raiga Fujimura, offering information and a proposal.
There had been not seven, but thirteen Servants summoned. Two for each of the non-Caster classes and one for the Caster. A Homunculus had been running around the city for the past week, and was the one that summoned Godzilla. That would have been a big problem, but it seemed that Taiga Fujimura was also a Master, summoning another Lancer that half his men had fallen in love with before Taiga allowed Lancer to cover her face with sunglasses and a paper bag. Desiring to save his Yakuza from destruction, Raiga summoned another Archer.
What the Fujimuras were proposing was a three-way alliance, which you accepted.
After that explosive first night, things quieted down for a few days as everyone seemed to go to ground. Your alliance kept an eye out for any enemy Servants, but none appeared where you could engage them. On the bright side, the serial killer that had been plaguing the city seemed to have stopped as well.
And then dozens of demons started appearing in the city, taking out not only a large number of Raiga's men, but also a black knight Berserker that had attacked the Tohsaka Mansion in the confusion which had been forced to retreat into a pair of demons.
At this point, Caster, a long-haired woman in a white dress with red markings, appeared before you and asked for relationship advice, stunned and not understanding why her Master was proposing to her. Eventually, lacking any solid answer to her dilemma, she offered a 'Contract' to you in frustration, which would be an experiment to see what she could do with one of her Noble Phantasms.
A wish was required, and while she couldn't grant your first two wishes (World Peace and to win the Grail war both being out of your unusually high karmic potential, she said), she was able to grant a wish so that Irisviel would live a full life without the Grail killing her.
It was granted, giving you a purple gem the size of a chicken egg and manifesting the Lesser Grail outside your wife. The Lesser Grail was then stolen by Caster, taken to an urban area where the ley lines crossed, to see if she could either absorb enough mana to power the Grail without going through the rest of the Servants or to unleash her strongest Noble Phantasm.
It took a command seal to prevent Saber from charging after Caster recklessly in frustration.
The next day, the Church made an announcement that Caster was causing the influx of demons in the city, necessitating her defeat so that the secrecy of the Moonlit World could remain secret.
With your knowledge of where Caster had set up her base, your alliance used Archer's 'Tactical Genius' to ambush her as she was trying to fight off the other Saber, a girl in a maid uniform wielding an invisible sword.
Of course, it was the time of your arrival chaos broke out in the area.
The black and red Assassin, along with Gilgamesh, made their appearance, before Godzilla and both Riders approached.
Faced with most of the remaining Servants against them, in addition to several magi, Yakuza, and the security team that some pharmacy company had assigned to the other Saber's Master, Caster was crushed rather quickly, though it was the Saber in the maid outfit that managed to strike the final blow.
It was at that opportunity that Godzilla took a step and crushed Taiga's Lancer, before attempting the same on Gilgamesh and almost getting killed by numerous swords from the Gate of Babylon (before disappearing due to a Command Seal), starting to activate the Lesser Grail that had been stolen.
It was at that point that your Saber tried to claim the grail for themselves, trying to kill the other Saber before conflict broke out more heavily. He even used his final Noble Phantasm, 'Living Sword of the Demon King' to try to kill the other Servants, but being the first to attack meant that everyone attacked him.
He died, but not before making a wish to bring his master into the world.
A large beast of darkness consumed the Lesser Grail upon his death, but Iskander, Gilgamesh, and the black and red Assassin killed the beast, leaving only a large black spike embedded in the ground.
With one Lesser Grail used, everyone started their separate ways, before the Assassin tossed you a black sphere with two spikes, saying that you needed it to survive until you made your adoption, and to use the 'Grief Seeds' he called them on your 'Soul Gem'. He also stated that Kirei was almost ready to speak to you, which you dreaded.
The next day, Raiga had his Servant use 'Tactical Genius' to not only kill the Tohsaka master, but also the moderator. It was also used to start harassing Gilgamesh, before he lost patience and blasted Fuyuki to rubble with Ea to make sure that the 'Tactical Genius' wouldn't be able to escape.
Godzilla, Raiga's Archer, and the forty aspects of the traditional Assassin (which had escaped notice until then) were slain in the destruction. More mundanely, most of the Fujimura Yakuza, including Raiga, were killed, along with most of the population of Fuyuki. Surprisingly, Tagia survived, latching onto the child master of the last Saber, who had also survived.
Both Riders charged Gilgamesh in fury, before both being cut down by a team of Gilgamesh and the black and red Assassin, leaving the girl in the maid outfit the last remaining Servant against a combination of Gilgamesh and the Assassin.
The second Lesser Grail manifested in the area where the first one did, but started spewing black mud. You raced to try to get there, only to be stopped by Kirei Kotomine while Gilgamesh went on ahead.
