Garasu no Kamen Forum
I am afraid I do not have the time to admin/moderate a forum of my own, but this site is affiliated with the forum:
It's in Italian but it contains an English section. Everybody is very kind and friendly.
I also recommend the following forums:
Shoujo Manga Outline (Italian)
Il Grande Sogno di Maya Fans Forum (Italian)
Glass Mask Forum (English)
Glass no Kamen: Forum (French)