On Redhat Linux6.1 ja and 6.1ja update: GlyphVector with build 1.3.0beta-b05.
The intervals between characters is iregular with Japanese font.
This phenomenon will be confirm with WadaLab Gothic font and Watanebe
Mincho font.
WadaLab Gothic font and Watanebe Mincho font are built into Redhat
Linux 6.1ja and 6.1ja update by default.

Testing locale is
[Duke@target /]$ locale
LANG=ja
LC_CTYPE="ja_JP"
LC_NUMERIC="ja_JP"
LC_TIME="ja_JP"
LC_COLLATE="ja_JP"
LC_MONETARY="ja_JP"
LC_MESSAGES="ja_JP"
LC_ALL=ja_JP

To reproduce,
1. Execute attached program (GlyphVecterTest.java) on Redhat Linux6.x ja.
2. Select font WadaLab Gothic and Watanebe Mincho.
3. Change Font size 24 to 14 16 18 .... .