As far as the Kirby/ Fumu & Bun not being related in name, that's not entirely true: it just precedes modern Japanese, and therefore is not a readily-identifiable example. The final N character () is discussed thoroughly in Hadamitzky & Spahn's Kanji & Kana, 3rd Edition, and even [http://en.wikipedia.org/wiki/Gojuuon The Other Wiki] mentions it in their opening paragraph on the preferred method of collating Japanese.

Therefore one (albeit somewhat archaic and dated) rendering of their names would have them looking like 'Fumu' and 'Bumu', a point driven home with the fact that 'Fu' and 'Bu', in kana, are the same character, just with softening marks for the 'Bu'