I use TextMate for text editing in OS X and love its clean interface and features, but the defaults do not allow Japanese input and choosing Fonts has been problematic. Never fear. Hetima san, the developer of SafariStand, released a bundle called CJKInput for TextMate to allow Japanese input, and has a font to boot. I searched a few times for this in English and Japanese, but for some reason never came across it despite its having been around for quite some time.
At any rate, you can download CJKInput, and unzip and copy the tmbundle file into:
Hetima’s Font-Forged, Mono-Space Japanese font ForMateKonaVe.ttf is here, so you can install that in the normal way. Enable it in TextMate Preferences, and away you go. The font is an amalgam of a Japanese font and the open source Bitstream Vera Sans Mono, so it looks good too.