Iceland

Iceland (アイスランド) is a Nordic island country in the North Atlantic.

Background
Skírnir’s Staff (スキールニルの杖), a spiritual item with four runes carved into it, is based on Norse mythology from Iceland.

Homecoming Arc
Radiosonde Castle started floating up from Iceland.

Magic God Othinus Arc
During the Anti-GREMLIN Alliance conference in New York, Elizard guessed that Sargasso was located in the North Sea or the sea near Iceland.

Coronzon Arc
Iceland was mentioned when Tokiwadai Middle School students were trying to decide where to go on a "vacation" after Academy City was shut down.