Sagara Hyouma

A Master of the “Black” camp. He was in charge of Assassin. He had already died before the main story in the volumes had begun. Originally, he was a magus that appeared in the pre-story of Fate/Apocrypha recounting the story of Jack the Ripper and her Master. He tried to sacrifice Rikudou Reika in order to summon Jack, but he was betrayed by his Servant immediately after she was summoned and experienced the misery of being slaughtered as a Master.
Just like Atram who appeared in the animated version of Fate/stay night UBW, he used magecraft that exchanges living sacrifices as compensation for his spells. In Sagara Hyouma's case, he utilized a hybrid of Japanese and Western cursing techniques and made fortune by establishing security for buildings and protection for people in exchange for sacrificing human lives. His Western cursing techniques consists of techniques he obtained from the Icecolle family that the “Black” Master Celenike is a part of since their disciplines intersect. The way he combined the techniques of a completely different family into his magecraft demonstrates how he is a typical example of an Yggdmillennia magus in a certain sense.
He wouldn't have had any problem summoning Hassan as Assassin, but he judged that doing so would be disadvantageous under the current conditions where a certain amount of countermeasures against all nineteen different Hassans have been created over the many repetitions of subspecies Holy Grail Wars. Based on the shallowness of his own history as well, he tried to secure victory with a modern Heroic Spirit. However, that turned out to be a fatal mistake, though he naturally could never have imagined that the woman he had approached merely to use as a sacrifice was in fact a far greater monster than him.
…This is a digression, but Sagara Hyouma is most famous for the misprint regarding him in Volume 2.
No, I really wonder how I overlooked that. I'll definitely correct it in the second edition.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia