1. java -jar rhdm-installer-7.0.0.GA.jar
2. In "2. Installation Path", click "Browse"
3. Dialog box pops up. Multibyte file/directory names are rendered as squares. (See Installer-dialog-box-rhdm700.png)

Reproducible regardless of LANG (en_US.UTF-8 or ja_JP.UTF-8).

-Dfile.encoding=UTF-8 doesn't help.

BRMS 6.4.0 Installer doesn't have this issue. (See Installer-dialog-box-brms640.png)
EAP 7.1.0 Installer doesn't have this issue as well. In EAP case, users can choose "Japanese" at the begging of the Installer.