fonts and characters

I note that I have somehow failed to install or configure my system so
that my terminal does not render characters outside of my alphabet at
all.

Typically, I run my IRC sessions in tmux inside a xfce-terminal, but I'm
not sure how to get proper rendering of characters for other alphabets
(cyrillic, kanji, etc).  Is this a trivial mistake on my part or is
something slightly more interesting going on?

sean

p.s. firefox renders other alphabets (for the most part) just fine.