For future reference, this fixes all woes:

sudo apt-get install xfonts-wqy

UPDATE: a much better solution is to install a pretty TTF font and then make all the characters bigger.

sudo apt-get install fonts-wqy-zenhei fonts-wqy-microhei

Then create a file ~/.config/fontconfig/fonts.conf with the following contents:

<?xml version = "1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
  <match target="font">
    <test qual="any" name="family" compare="eq">
      <string>WenQuanYi Zen Hei</string>
    <edit name="pixelsize" mode="assign">

Oh yeah: am trying to learn some Chinese characters! Prompted by the arrival of an enormous Chinese phone at work.