If CJK characters are contained in a JMenu, It is difficult to recognize
the shape of character clearly because many CJK characters are
constructed with many line strokes. It is noticeble with bold font
and font size is 12 point as default.
Attached MenuTest.java includes 2byte font in Menu. You can see the situation
with this program.


Two suggestions:

1, Font rendering quality improvement is the one of direct solution.

2, Change the default font definition bold to plain.
   Bold font of MetalTheme is defined in
   src/share/classes/javax/swing/plaf/metal/DefaultMetalTheme.java

  *This is the way of definition to check the plain font temporary with
   java option.
   If invoke MenuTest without this option, bold font will be displayed.
   java -Dswing.plaf.metal.controlFont=Dialog-12 MenuTest

   To use plain font instead of bold font, It affects the jdk design though.
   But the design that plain font as default with JMenu was using with jdk1.2.2.