Finally figured it out...

I've had this little problem with combining Japanese + Java. The jist is that I've never been able to get Java to handle Japanese characters, no matter how I set things in Eclipse or setup Java, I've never been able to get it working.

...turns out I just needed to skip step 1 and go straight to step 2. Apparently, the console in Eclipse can't handle the characters, but everything else can.

So, for the past ~1 year, I've been unable to work with Kanji in Java simply because I haven't tested it outside of one specific area.

Technical shorthand to this: "System.out.print("新しい")" displays "???", and "JOptionPane.showMessageDialog(null,"新しい")" shows the kanji correctly.