I feel that the solution may be converting the prefecture name to Latin script too early in the process. The sixth Japanese prefecture is written in Japanese with the Unicode code points U+5C71 U+5F62 U+770C (U+770C just means, more or less, "prefecture" and isn't especially important). A solver might wish to proceed on a character-by-character basis. Checking the Unihan Database on the https://unicode.org/charts/unihan.html website gives the following results for the kJapaneseKun property:

  U+5C71 = YAMA
  U+5F62 = KATACHI KATA ARAWARERU

with, fortunately, still T as the 7th letter.

So, I feel that the "list item" column could be updated to:

  YAMAGA(T)A (or
  YAMA KA(T)ACHI
  KATA ARAWARERU)