Jubstacheit von Einzbern (ユーブスタクハイト・フォン・アインツベルン, Yūbusutakuhaito fon Aintsuberun?), also known as Old Man Acht (アハト翁, Ahato-Ō?), is the eighth head of the Einzbern family. He might have resigned the position because Illyasviel called herself the head of the Einzberns.
Jubstacheit is an artificial intelligence made to control the Einzbern Castle, Golem Jubstacheit (ゴーレム・ユーブスタクハイト, Gōremu Yūbusutakuhaito?). At the end of the ninth century, Justeaze Lizrich von Einzbern was born quite by accident, having no relation with the Einzberns' technology. The Einzbern Magi, who had been trying to regain the Third Magic on their own, created Jubstacheit, a golem that had all their knowledge, and ordered him to reproduce her. Before he could do it, Justeaze succeeded in performing the Third Magic and the Magi, who fell behind her, accepted that their reproduction project had failed, so some of them left the Einzberns and the others killed themselves.
Even after they all had gone, Jubstacheit kept coining Justeaze-type homunculi and took some centuries to reach the same conclusion as the Magi's. It manufactures humanoid golem terminals and Acht is the eighth and last one. Acting as family head, Acht was created after Justeaze's era, but has presided over the family since the Second Holy Grail War. He led the family in their attempts to reclaim their lost Third Magic, but suffered failure twice.
During the Third Holy Grail War, he suffered defeat on two fronts, with the family's Servant, Avenger, being quickly defeated and the destruction of the Lesser Grail. With the Grail being unable to manifest even before the victor emerged, the war became meaningless. He reflected on the design and decided to "cover" the vessel of the Grail in a humanoid shape in order for it to be able to self-manage. As the he and the elders of the family sought victory over all else, he hired Kiritsugu Emiya to act as their representative to make up for their weakness in combat during the previous rituals, and sought out a relic to summon the "strongest Heroic Spirit of the Sword."
Jubstacheit is the "old magus king" of the Einzbern castle. While long lived, Kiritsugu feels an "astute light" emitting from his eyes to hide any trace of senility, and his white beard makes one think of a frozen waterfall. He gives off an imposing bias and pressure each time Kiritsugu catches his gaze. He has a close relationship with the Talbot farm that produces early autumn Darjeeling, and he has served the tea only to special guests for a number of years. Kiritsugu shows him respect, but they have fought over details such as installing a telephone line and power generator, which is heresy to such an established magus.
Since taking the family under his leadership, they have changed their goals from "seeking the Holy Grail" to "winning the Grail War." Much like the rest of the family, he wishes to reobtain the Third Magic, but he has only known the pain of defeat in his efforts to reclaim it since the time of the Second Holy Grail War. After suffering failure during the Second and Third Grail Wars, the anxiety of facing the third opportunity during the Fourth War is extraordinary. All of his emotions can be condensed into the single word "Achievement", and Kiritsugu believes his spirit likely only has this rigidity towards achievement left.
Fate/Zero Drama CD
The product of Jubstacheit's goal of a humanoid vessel for the Grail is the Homunculus, Irisviel von Einzbern, nine years before the Fourth War. He creates her with the purpose of being a vessel capable of self-defense, but Kiritsugu finds her to be lacking. He wishes for something without a sense of self because an object that can decide on its own will is no longer a tool. Upon Kiritsugu complaining and asking for a more compact animal form, Jubstacheit reveals that he has thrown her naked into the homunculi disposal yard as a test, planning to see if she can survive for days in the forest with hungry wolves and evil spirits. Kiritsugu is astonished, but Jubstacheit states that all he needs is a vessel that will survive until the Greater Grail ritual. If she does not survive, he will simply acknowledge the defects in his design and prepare a new vessel in accordance with Kiritsugu's specifications. Rather than let it play out, Kiritsugu quickly rescues her, noting the entire ordeal was to clear the humiliation from Kiritsugu hurting his pride.
Jubstacheit summons Kiritsugu and Irisviel before the advent of the Fourth Holy Grail War to present them with Avalon, the relic to summon King Arthur that they had requested to be excavated from Cornwall. He confirms the status of the vessel of the Grail with Irisviel, and his eyes shining with "insane strength" declares, "This time... no one must survive. Kill the six Servants; this time we must acquire the Third Magic, the Golden Grail." Although both Kiritsugu and Irisviel answer him fervently, Kiritsugu's true mission lies elsewhere in obtaining his dream of world peace.
The ritual ends in failure, and he learns of Kiritsugu's betrayal in the destruction of the Holy Grail. Rather than seeking to punish he who would have been unable to do anything but silently accept it, he instead never again allows Kiritsugu into their forest's Bounded Field and keeps him away from his daughter, Illyasviel von Einzbern. Kiritsugu believes that he either wishes to exile him to carry the shameful title of a traitor for the rest of his life, or to impose the most severe punishment that can be inflicted by never allowing him to see his daughter again.
Jubstacheit is not mentioned by name, but Illya, referring to him as grandfather, mentions being taught details about the Holy Grail War by him. He described Japanese people to her as a "neck-cutting tribe who die by having their necks cut off while sitting Japanese-style."
Jubstacheit appears in the anime adaption of the Unlimited Blade Works (route) in a brief scene. In Illya's flashback, she asks Jubstacheit where Kiritsugu is. Jubstacheit does not deign her a response and simply walks away.
Jubstacheit is skilled in making homunculi, and claims that Irisviel is among the best of his works in recent years. She is constructed to be harder to break than a regular Grail vessel, and designed to prevent herself from being broken. He cares little for the well-being of his creations, prioritizing his pride as a designer over any pain they may experience.
- Fate/Zero Anime Visual Guide II, p.21
- Fate/stay night - Fate route - Day 11: DragonSlay - Replay of the legend
 Fate/stay night [Unlimited Blade Works] Season 2 DVD Booklet Animation Elements p.19-27 [T]
• The origins of Einzbern
A factory originally created by the students of the magician who realized the third magic. Began in the year 1 AD.
They attempted to reproduce their master’s miracle, but couldn’t do it themselves, so as an alternate plan they tried to recreate a specimen identical to their master and have it reproduce the magic.
After nearly 900 years of effort, Justeaze—the homunculus who would come to be called the Winter Saint—was forged.
She was a model that strayed from what the magi had intended, created completely by accident, but her abilities were equal to or above those of their master.
The magi should have been elated about Justeaze, but they couldn’t be happy. After all, she was a mutation that was born regardless of their own techniques or skills.
Even if that specimen was to reproduce the third magic, that conclusion would be harder for them to bear than 900 years of failure.
The magi deperately attempted to create a homunculus that excelled Justeaze by their own techniques.
The artificial intelligence created to act as the castle’s central management—the golem Jubstacheit—was the pinnacle of their craft, and became the father of all homunculi created at Einzbern.
Justeaze succeeded at proving the third magic.
However, it was not cost-effective. Justeaze’s use of the third magic was like careful knitting. It would take several years to save just one person, making the salvation of the entire human race virtually unattainable.
In addition, while Justeaze herself did not age, her body was so frail it would take little to kill her, so she could not leave the castle.
Since her intelligence and mentality were also unaging, she did not develop at all. From an outside perspective, it was as if she was repeating a single day for all eternity.
If she were to leave the castle she would be freed from this “single day,” but the act of leaving the castle signified an easy death for Justeaze.
In the end, they accepted that humans could create something that surpassed humans, but not something that could save humans.
… Or perhaps they would not have failed if a miracle like Justeaze had not occurred.
The magi despaired the limits of their abilities. Some abandoned the castle, while others took their own lives.
The homunculi left at Einzbern were abandoned by their creators, but in their purity, they continued to operate the factory for the sake of the creators’ ideology—the salvation of humankind, the reproduction of a miracle.
From then on, all homunculi created at Einzbern were based off of Justeaze.
Jubstacheit created a humanoid terminal unit, and used it as the manager of Einzbern. Though by the end he operated even Acht (the eighth humanoid terminal), he did not possess a personality.
He only included the necessary “humanity” to operate the castle and reproduce the third magic into each of his humanoid terminals, and made them act like humans.
Jubstacheit is essentially an automaton that cannot progress, but continues operating in perpetuity. His way of existence is just like an old clock ticking away, being forgotten by people before running down.
• The great grail
Five hundred years after the magi departed from Einzbern, a model plan was devised for a wide-area operation device for the third magic using Justeaze.
Einzbern had determined that reproducing Justeaze was impossible.
Their plan of keeping Justeaze safe because she was a unique and valuable model switched to a plan to use that unique model to mass-produce miracles.
(This was not Jubstacheit’s plan, but a consensus of opinion within Einzbern. Because the homunculi were pure, they chose the method with the greatest probability of success. In fact, Jubstacheit was the only intelligence that voted against this.)
Justeaze could only use the third magic on one human over a period of decades. Therefore, using Justeaze as a frame, they would create a “greater” magic formula and save many humans at once.
The plan was to disassemble her magic circuits and replace them with a magic formula, creating a humanoid universe—the great grail.
But Einzbern alone could not start this project.
They were no more than dolls. They had no way to live in the outside world, and they couldn’t handle the complexity of human society.
To create the great grail and reproduce the third magic, they needed understanding and cooperative humans.
Then, in the year 1800, a guest arrived at the winter castle that had continued to produce homunculi.
Makiri Zolken. A magus who had devoted his life to eliminating all the evils of the world, the evils of humanity.
(At this point, Zolken was mostly disillusioned. He knew it was about time to give up, but calling on Einzbern was his last hope. He met Justeaze, and felt a complicated mix of emotions—hope towards fulfilling his ambition, jealousy at her ability to use the third magic, and pity for Justeaze’s eternal youth causing her to “repeat the same day.”)
With Makiri’s understanding and Tōsaka’s cooperation, Einzbern began to create the great grail.
However, once they started, they determined that Justeaze alone was not enough.
They could create a great grail. They could create its core. However, to operate it they would need vast amounts of magical energy, and a lesser grail to control it.
Makiri and Tōsaka devised a ritual to collect magical energy using Justeaze’s ability to connect with the root: the grail war.
Despite being unable to reproduce Justeaze, Einzbern created a lesser grail with similar abilities to hers.
After 10 years, the project was finally complete.
The grail war ritual was successful, and the great grail lit up.
But its first operation ended in dismal failure.
There was no flaw in the great grail itself.
The problem lay in the craftsmen and magi who participated.
Instead of using the precious magic reactor core for the sake of the whole planet, the magi killed each other out of a desire to use it for the sake of their own race or society.
Einzbern had been unable to understand the thought processes of the humans who operated the great grail.
• Irisviel and Illyasviel
Einzbern learned from the failure of the grail war and changed their plans.
Justeaze no longer existed.
While preparing to restart the great grail, they returned to their original goal and focused on creating a perfect homunculus.
As a result, they created Irisviel, a homunculus with the function of a lesser grail. They expanded on her further and Illyasviel, a homunculus that was the pinnacle of Einzbern’s technique, was born.
This is a digression, but separate from the winter castle is the tuners’ building (a small house), inhabited by a family of human magi, not homunculi.
Since the homunculi cannot negotiate with human society, the tuners went into town in their place and barter for needed materials. Traders, essentially.
Still, they are a talented magus family, and possess strong artistry. Humans without strong aesthetic sense could never take care of Einzbern, after all.
The tuner family’s numbers dwindled along with Einzbern’s decline, and in the end only one remained.
It seems he often worked in the castle as a butler, teaching the secluded, medieval-minded homunculi about the outside world.
It’s unknown what kind of conclusion that tuner chose after Illya lost and Jubstacheit shut himself down.
• In summary: so what is Einzbern?
A factory in which homunculi continued operating towards the ideals and goals humans had given them, after the magi had left.
Jubstacheit is something like the factory’s central management program. A monolith. Acht is his terminal.
Even after their creators had given up and died, the homunculi in the winter castle devoted themselves to making their masters’ dream come true.
What lies at the basis of the Einzbern factory and many discarded things is the purity of machines.
Imagine a doll that can speak to its owner, but only a few phrases.
“Hello,” “thank you,” “I’m sorry,” “good night”—“I love you.”
These reactions delight the buyer, but it’s clear that they will soon be disappointed.
“No matter what I say, the doll can only say predetermined phrases. It just keeps repeating that tired old ‘I love you.’ ”
Realizing that the love the doll speaks of is a false emotion, the buyer will likely discard it eventually.
But humans are the ones who see that as empty words and a manufactured fake.
Even if it doesn’t have a “heart,” even if it’s only repeating the same words, there are no lies in the actions of machines.
They innocently carry out the task they were given.
“I love you.”
Though abandoned, forgotten, and scorned as out-of-date dolls, they continue to carry out their mission, unchanged from the time they were designed.
Machines do not lose their worth when a newer model appears.
Their worth (life) ends when humans can no longer bear that purity.
城の中枢制御用に作られた人工知能 …… ゴーレム・ユーブスタクハイトは彼らの技術の結晶であり、アインツベルンで作られるホムンクルスたちすべて の父となった。
ユーブスタクハイトは人間型の端末筐体を製造し、これをアインツベルンの管理者として使用する。最終的には アハト(八代目の人型端末 )まで稼働するユーブスタクハイトだが、彼に人格は存在しない。
(ゾォルケンもこの段階でほぼ夢破れている状態。もう諦めるべきだと分かっていながら、最後の希望でアイン ツベルンを訪れた。そうしてユスティーツァに出会い、悲願達成への希望、第三魔法を可能とするユスティーツ ァへの羨望、不老の代償に『一日を永遠に繰り返す』ユスティーツァへの哀れみ等の複雑な感情に とらわれる )
『ごきげんよう』 『ありがとう』 『ごめんなさい』 『おやすみなさい』—『あなたを愛しています』その反応に喜ぶ買い主だが、すぐに失望するのは 明白だ。
- Fate/hollow ataraxia - 10/09 - Emiya's - Sugar candy teatime
 Fate/Zero Season 1 Boxset - Drama CD 1
- Fate/Zero Volume 1: The Untold Story of the Fourth Holy Grail War - Act 1 Part 2 -282:14:28
- Fate/Zero Volume 4: Flames of Purgatory - Epilogue: Five Years Later
- Fate/stay night - Fate route - Day 3: long day, long night - Bad End: Forest of no return
- Fate/stay night [Unlimited Bladeworks] - Episode 15: "A Battle of Legend"