Emiya Norikata

Emiya Kiritsugu's father. A genius who, by perfecting his family's internal (small-scale) time manipulation sorcery, managed to earn a sealing designation despite being a mere fourth generation magus.
He evaded capture by the Association for over twenty years, and finally ended up hiding himself away on a small island in the tropics. His wife was killed by pursuers from the Association, but Kiritsugu had only just been born at the time and so has no memory of the incident.
The sorcery of the Emiya family involves accelerating or stagnating the flow of time within a reality marble, without interference from the world. Norikata plumbed the depths of this sorcery, and hatched a scheme to shrink a boundary field until the resistance was almost zero, then infinitely accelerate time within it. His belief was that by observing the end of the universe, he could arrive at the “Root” that lay beyond it. But though the theory itself was promising, he would require a period of hundreds of years to complete the experiment. In order to solve the life span problem, he reluctantly began researching methods of becoming a Dead Apostle.
The resulting tragedy is described in the interlude at the beginning of the fourth volume.

Fate/Zero material: Fate/Zero Encylopedia