Fuyuki

A certain provincial city. In these novels, the Holy Grail War doesn't occur there, of course, and as a result, the mayor of Fuyuki, Himuro-san, doesn't get a pained stomach from that Great Fire Disaster.
And of course, that red-haired boy is living there with his original surname unchanged, but still having a honest and upright personality (as shown in his appearance in Capsule Servant), and likely going through days with a love comedy-like tone, along with a twin-tail magic-fist user and her cheerful little sister who laughs like a high-class young lady.

Fate/Apocrypha material: Fate/Apocrypha Encylopedia