How do I set the font for JOptionPane and for the tooltip?

For JOptionPane, I tried instantiating the object, set the object's
font, then call its showXXXDialog() method, but it doesn't work. For
the tooltip, it is the tooltip for a JComponent (label, textfield,
etc).

What I want to do is to be able to display Japanese text in the
JOptionPane or in the tooltip, while running on an English OS.