And in the case of Japanese, the extra field seems to be utterly essential, because the same characters in Kanji might be pronounced in radically different ways.

http://www.localizingjapan.com/blog/2011/02/13/sorting-in-ja...

  There are four Japanese women whose names you have to sort: Junko, Atsuko, Kiyoko, and Akiko.
  This does not seem difficult, until they each show you how they write their names in kanji:

      淳子 (Junko)
      淳子 (Atsuko)
      淳子 (Kiyoko)
      淳子 (Akiko)