Komachi'd be Italy because they still use ferryboats a lot as transport method.
Aya'd be Netherlands, because she manipulates the wind, and the country is full of windmills.
Utsuho'd be Iran, because of the nuclear weapons they have.
Letty'd be any country from northern europe (Swedden, Iceland, Denmark, Norway or Finland)
Koishi'd be brazil. (My country) Because she is green and yellow. :V