Do you have screen grab of what it looks like when you used: Arial, メイリオ, Meiryo, MS Pゴシック, MS PGothic, ヒラギノ角ゴ Pro W3, Hiragino Kaku Gothic Pro, sans-serif;
I've been using this for a number of years and my Japanese colleagues never reported issues. I've used it here too: http://www.cmegroup.com/ja/. Would be interested to see what conflicts you had.
just FYI,
The latest OSs (Win10 and recent Mac OS versions) have use another fonts set as default in Japanese.
It still supports the traditional fonts, but looks different and old.
Taishi Yamada, what are the new font names for Japan, do you have any local websites that are using them?
Does anyone know of a good font-family stack for Vietnamese?