The unnamed man is the Master of Avenger Louis XVII "After" the Holy Grail War in Fate/Requiem
Profile
Background
A person from the old generation of humanity before everyone was born with a Holy Grail within them, Louis' Master was a deeply disturbed individual with severe mental problems. He worked out of a small workshop in Akihabara and attended group therapy sessions where he became aquainted with Erice Utsumi.[1]
Appearance
Louis' master is a massive man twice the size of the then nine-year-old Erice, with a well developed, muscular body that could easily be mistaken as a servant honed through some ascetic practises. His eyes are described as dark, but whether this pertains to their colour or some other facet is unclear.[1]
Personality
Erice describes Louis' master as a person lacking in spirit who doesn't talk except when necessary. Despite this impression, he has strong emotions hidden within, having strong feelings about Mosaic City and humanity's place in it, lamenting modern humans reliance on Heroic Spirits.[1]
Role
Fate/Requiem
Louis' Master is a person Erice met in group therapy. Taking it upon herself to help him, she became friends with his servant and him, spending time at his workshop regularly until his nature as a serial killer was discovered. having killed an investigator who was after him, he attacked Erice only to end up being killed by her in turn.[1]
Abilities
While lacking any abilities as a mage, Louis' Master possesses great skill as a leather worker, creating bags and children's shoes that sell out almost immediately. The 'artworks' he creates from living people are looked upon as avant-garde pieces that failed to raise suspicion as acts of murder for nearly an hour after their appearance in public. He also seemed to possess some ability in combat, killing an investigator with a head knife and causing Erice multiple injuries before being killed by her.[1]