<fontconfig>

  <alias>

    <family>Source Han Serif JP</family>

    <default>

      <family>serif</family>

    </default>

  </alias>

  <match>

    <test name="lang" compare="contains">

      <string>ja</string>

    </test>

    <test name="family" ignore-blanks="true">

      <string>serif</string>

    </test>

    <edit name="family" mode="prepend">

      <string>Source Han Serif JP</string>

    </edit>

  </match>

</fontconfig>