They've got old-fashioned cars, trains, and telephones, but wealthy land-owners still have armies of servants, so it's probably analogous to some time between 1900 and 1940. Maybe something like Belle Époque or interwar France, judging by the names. Oh, and there's a country of animal-eared people nearby, which is Taishou or late Meiji Era Japan, where the rest of Itou Hachi's works are set.