One day, around twenty years ago from the current events in Fate/Strange Fake, an aging priest named Dilo was assigned to a mountainous region of Spain. He heard from the villagers that there were evil spirits in the mountains, and decided to investigate. There, he came across a young boy eating meat with some lynxes - the boy ran away, and Dilo discovered that the child had been eating jerky he had apparently prepared himself from a bear carcass not too far away. The boy soon approached the curious priest on his own, and striking up a conversation with the feral child, the priest learned that the boy had lived in a small mountain village most of his life with his family, but a "goblin" had suddenly appeared that destroyed the village and sucked the blood out of its residents, only to eventually be killed for good by the boy's dying mother. The boy was the only one left out of that massacre, and had been living on his own on the dangerous mountainous paths, killing prey with his bare hands to survive. Dilo decided to bring him back to the village he was staying at for the time being.

A few months later, after the boy adapted quickly to village life, Dilo brought a friend of his to take a look at him. The friend was another priest by the name of Delmio Cervantes, who was dubious when Dilo told him of the boy's physical prowess. Offering a silver coin to the child, Delmio then threw it at the speed of a flying bullet, thinking it would scare the boy - only to turn and find that he had simply caught the coin with his bare hand out of thin air. Deeply impressed by the child's physical abilities, Delmio took Dilo's suggestion to train the boy in martial arts and make him a part of the Church as an official member.

The boy's name was Hansa, and being taken under Delmio's wing, he took the name of his foster father and became the Hansa Cervantes we all know and love.

Over the years, he trained with Delmio, and eventually took an occupation that was connected with the monster that had destroyed his village so long ago - he became an Executor, one who eliminates beings of absolute evil in God's stead. At some point in his life, Hansa allowed his body to be changed by the Church's technology, making it so that around seventy percent of it was made of consecrated metal and gadgets that were specifically made to destroy heretical beings.

In the events of Fate/Strange Fake, a strange Grail War starts on American soil - one that is actually compromised of a "Fake" Grail War that was merely a ritual to power the True Grail War. The Church, always taking on the role of a neutral Overseer in Grail Wars, sends the closest representative of the Church to the area - and it happens to be Hansa Cervantes, with his team of nuns called the Quartet. Hansa, uncaring of the in-factional fighting of the war, yet deeply annoyed by the "joke of a war" he's now involved in, goes to see Orlando Reeve, Chief of Police in Snowfield, Nevada, who is suspected to be one of the conspirators who made the war happen in the first place. He proceeds to needle the police chief because he's a giant troll who can't help himself, but just when Orlando is about to arrest him, a Servant attacks the police station. It's Assassin, a woman with no name who was considered a zealot in her time who is determined to kill the "infidels" involved in this Grail War. After launching a furious attack on the police chief and his police force, a man suddenly appears on the scene - Assassin's Master, a man by the name of Jester Karture.

Jester Karture is a Dead Apostle - a vampire of sorts. He proceeds to mock everyone, making his intentions clear that he only cares for his Servant, who he eventually wants to love and destroy like the monster he is. Fending off Orlando and his team's attacks easily, he suddenly finds that his efforts are stopped short by nothing else but a cup of coffee to the face from a certain priest. The two start to fight with each other, and Jester asks why Hansa, as a neutral overseer, is throwing aside his position to fight with Jester, a Master he should technically be supporting in his role. Hansa merely remarks that Jester has done nothing but show himself to be a villain, and a Dead Apostle like him doesn't deserve the Grail. The two fight a battle of equals, before Hansa reveals he has a grenade launcher in his hand and blasts Jester with it. The vampire manages to escape in the form of a small boy, and Hansa sends the Quartet to track him down.

The next day, Hansa greets Orlando's squad at the church, who have approached him with help to shelter a Master during the war - a comatose young girl in a hospital whose Servant is literally the Plague. Fun! There he meets Flat Escardos, a strange young teenager of a Master who compliments him on his cyborg body.