Mezamashii can also have the meaning of Brilliant, and many Japanese-English dictionary say so, but I think this word is rather used to describe "noticeable" or "marked" change in a positive direction. For example, the sentence "a marked improvement" can be said "めざましい進歩(Mezamashii Sinpo)" in Japanese. Unlike the word Brilliant, you can't use Mezamashii with anything haven't changed. When you want to talk about some static matters, you'd better to use what I have answered.

Wakatta :D and what about Mezamashii ? isn't mean Brilliant ?

You can say "最高の(something)" or "とびっきりいい(something)". In this case, it will be "最高の日本人クラブ" or "とびっきりいい日本人クラブ".

brilliant = 最高　（さいこう）；すばらしい

Oops (above)