who's that girl in the right?

I believe she's an original character from the LH game. Can't remember her name.

Which one do you mean? The blonde? She's Sarah Mcdougal.

No, the girl in the front, on the right side from our view.
Naru, Mutsumi and ?. I've read the manga, but I can't recall her either.

...On another note, I'm reminded of Eva's castle-in-a-bottle.

She is a girl from the DC (RIP) game.

I just had to download this game for my DC (: It feels good to pick up that white controller again...

Isnt it Kanako Urashima?

No, Kanako has black hair and much more sharp eyes.