I'm studying Japanese and need to write a lot of text with furigana. I've been using Word so far but my main concern is that entering furigana is not only quite clumsy (no hotkey) but what's more important is that once entered, you can't globally change either its font or its size; you need to change them one by one. This is a deal-breaker for me since my average text contains hundreds of entries. There is a hack you can do as pointed out by another guy on SU but I found that by using it I could (and did) break my document easily.
My question is: is there a software that is specifically designed to work with Japanese text that also has its UI in English? As stated above, I need something that has furigana editing as a first-class citizen.