The northern and northwestern regions are colder, rougher, and more isolated than the central kingdoms. They provide a different kind of horror: distance, weather, old traditions, empty roads, sea mist, and communities that survive by distrust.
The Northern Frontier is a harsh borderland of cold water, sparse settlements, raiders, old ruins, and dangerous wilderness. It is excellent for survival stories and rumors of ancient things that predate the current kingdoms.
Ys Principality is a remote island principality with distinct customs and strong local identity. It should feel independent, misty, and superstitious. Outsiders are tolerated but watched.
Randel Commonwealth is a northern coastal territory of ports, fishing towns, and practical politics. It sits between stronger forces and survives through trade and local alliances.
Grant Grand Duchy is best treated as a fan-map noble buffer region between Midland, Randel, and the northern world. Use it for old houses, castle politics, hidden family curses, and lords trying to keep supernatural incidents quiet.
These areas are useful when the AI needs to move away from central canon while still staying within the same world. They give room for original stories without colliding with Guts's main path.