Since I'm originally from Slovakia, I used my Slovak IME, which is convenient for me.
Incidentally, Slovak has its own romanization of Japanese, which uses almost nothing but Slovak letters and diacritics (plus "w").
Wikipedia pages about 九州 and 四国:
https://sk.wikipedia.org/wiki/Kjúšu
https://sk.wikipedia.org/wiki/Šikoku
The Hepburn system is an Americanism. Americans don't own the Roman alphabet or the way it should be applied to Japanese. Though Hepburn has official status in that it is taught in Japan, and used for the benefit of visitors. E.g. signs giving names of train stations or government buildings or what have you.
According to Wiktionary, ō is used as a long vowel in two Latvian languages, and in Swedish as a hand-written form of ö (not always a long vowel). Also in Silesian, a language in a region of what is now Poland.
aite
愛犬 aiken: beloved dog
相手 aite: companion, other party, opponent.
藍色 aiiro: indigo blue; 濃藍 koai: deep indigo.
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