Heinrich is part of the Zepter family, which was showing signs of moving recklessly since a few generations ago. Stumbling from resurrection to the creation of monsters, Heinrich escalated it when he used an entire town in north Germany for his experiments over twenty years ago. One such experiment was photographed in Bavaria. The Mage's Association could not remain silent after they found out, but he managed to escape with his life.
He found his way to America in order to use its land and people to research to his heart's content. He settled in a small village with a population of two thousand, Present Mountain, and continued his work there. He turned himself into a monster as of 1978, leaving a video behind to tell of himself to the hunters of the Association. His whereabouts remained unknown until twenty years after his departure from Europe when one of his creations appeared in the village where the police quickly killed it. Upon analyzing the corpse, it was confirmed by a magus that he was in that village.
The Zepter family cut themselves off from the outside world to carry out their experiments, and began on the wrong path without realizing it. Heinrich delved into madness while working on resurrecting the dead. While reviving the soul is a worthwhile pursuit for a magus, simply reviving only the flesh is comparatively boring. Specializing in only the flesh rather than the spirit, he feels that his family has done all they can in that area, that the practice is creating nothing more than mere toys. He seeks the Root like all other magi, and he is able to objectively think of all of that while still maintaining some sense of rationality.
He no longer cares about such rationality, as he has become "helplessly attached" to his toys. Describing his work causes madness to sink into him, destroying any sliver of intelligence previously shown in him. It can be said that his aim, course of life, interest, and hobby are all united, "to play with corpses." He speaks of his creations with glee, differing from other heretic magi who efficiently carry out their actions like ascetic monks. He loves them greatly, and they bring him true joy, but he does note that it is a shame that he has strayed from the path of humans and magi in the pursuit of his interest.
Heinrich wanted a monster that surpassed everything, and while there are monsters that possess the hearts of men, there is no need for a man to possess the heart of a monster. It was difficult for him to make a monster, and in spite of that, trying his best, he realized that he was hoping for monster itself instead of the action of creating it. Having gone through everything he could wish, feeling satisfied with everything he has done, the only thing left in his imagination was to turn himself into a monster.
Natalia Kaminski and her apprentice, Kiritsugu Emiya, travel to Present Mountain in order to hunt down Zepter. They are able to rent a room with little trouble, but sense that they are being observed. They are quickly assaulted by the townspeople, all under his control, and learn from one of them that he is located three kilometers away.
Zepter studies resurrection of the dead, but not that of reviving the soul and flesh that not even Magic can accomplish. The normal concept of Resurrection would involve restoring both the soul and flesh to return a lost loved one to life, but Zepter only focuses on the flesh. Without reviving the soul, it is just a moving body, a decaying corpse-eating ghost. His family has been immersed in obtaining the miracle of resurrection of the dead, initially focusing on reviving dead bodies flawlessly, followed by joining body parts together, and finally trying to create living beings by joining different body parts and giving the creature bodily functions. Wandering far from their original intention, they went from resurrection to the "creation of monsters."
They originally sought to join body parts to bring back the body in working condition. Flawlessly resurrecting the dead would be impossible in cases like senility before death and unexpected accidents causing death because such conditions would make the body no longer in the right condition to perfectly revive them as they were before death. They wished to pursue revival even if the limbs were severed or to revive the state of being short a limb. The further advancement of the resurrection technique was required, and the ability to join separated body limbs, joining the nerves and making them move, was needed to make up for it in case parts were insufficient. It was necessary to create a technique to fully operate the body by combining it, synthesizing, joining, and operating all body parts, regardless of their states.
Zepter has performed various experiments, from fusing babies and old people, creating a three-headed man, and even making a miniature version of Hekatonkheires. Within a workshop, he keeps magecraft tools, expensive magecraft books, a dissecting hammer, knives, and machetes, and has experiments like foetuses with five arms and fangs.
- Bavaria experiment: One of Zepter's early experiments in Bavaria was a combination of several humans with eighteen horse legs and a large black hole in its center, created by mincing it, affixing it together, and splitting it apart.
- Stableman: The man caring for the stable in Present Mountain has been completely hollowed out with the exception of the lungs and heart, leaving only the necessary organs to live and speak. He appears to be alive from the outside, but lacks even blood on the inside. He has a third arm on his back, long, powerful, and dried-up like that of a mummy.
- Twin-headed horse: There is a twin-headed horse, perfectly fused together with eight legs and two hearts, within the Present Mountain stable. There is a sticky substance where the two are joined, similar to molten chocolate, and two of the legs are wrinkled like the third hand of the stableman. It is able to function even with one of its hearts destroyed, and displays the capability to climb the wall of a house and gallop across a roof to escape.
- Sawyer: Sawyer is a man who acts as an assistant to Zepter. He has slurred speech and walks with a limp. Despite having his neck broken and dangling, he is able to function and attack, and even after being split down the middle, both parts feebly attempt try to help each other stand.
Zepter, "no longer of this world", has turned himself into his ultimate masterpiece. Having taken his human form into it, his form is like a mass of decaying meat made from the bodies of man and beast, with compound eyes and innumerable hands to grab opponents, in a form similar to a gigantic queen ant. While it has a mouth, he instead speaks with telepathy. His flesh is weak to piercing attacks, but his body scatters and absorbs bullets like a block of mud that quickly reverts to normal. He can take new prey into himself, his "village", to become one of his minions by opening his abdomen to swallow them. While it is a limitless body approaching immortality, his human body still exists within, thin like a mummy. His Magic Circuit is holding his body together, so the body will break apart and stop functioning upon it losing contact with his brain.
He has an oviduct that births fully clothed human beings from a viscous, gooey liquid to act as the two thousand villagers of Present Mountain. Due to the villagers being part of him, the entire village can be called "him", so no knowledge of those who enter or their locations escapes from him. Having made the population into his slaves, his "children" are completely cut off from feeling, restricting their brain activity. They follow his instructions emotionlessly, showing no trace of fear, hesitation, or anger when being gunned down. They wield various weapons like old-fashioned rifles, pistols, scythes, axes, bows and arrows, and other dangerous tools. They are able to communicate when needed to keep up the facade and discuss orders from Zepter among themselves, and many have been modified in his experiments. Even if killed, he can birth duplicates soon after to replace them, but they will all turn into lumps of meat should he be killed.