Japanese is a tricky language to make look good on a website due to the lack of support for Japanese fonts. Each operating system and or browser tends to use its own font.
From experience, I have discovered that the following fonts are the best:
font-family stack that I suggest using:
font-family: "ヒラギノ角ゴ Pro W3", "メイリオ", Osaka, "ＭＳ Ｐゴシック", Arial, Verdana, sans-serif;
Perhaps more support will be added in the future for Asian fonts such as Korean, Chinese, and Japanese.
Google is already taking one step into that direction. They now offer the font Noto which is available in a multitude of different languages, including Asian languages! You can find it here: