This is not so much a sequel as an OVA covering the very beginning of the story of Glass Mask. It begins with Maya, the girl who is not good at anything... aside from her fascination with all that is movies and dramas. Even her own mother believes her a useless girl. If a tv is on, she won't hear a word you say, if you send her out to deliver Ramen she may come back hours later, she can't remember a single formula for school... but she can recite any play she's watched once by heart. As a habit, she acts out her favoritedramas in the park to some kids where she is spotted by an mysterious old woman. You will see Maya's growing devotion as she finds the one thing she may be good at and the trials as she first establishes this dream.

This series of Glass Mask is good for two instances. One: A taste to see if this is a series you would like to watch in full or to have someone else watch to get them hooked. Or if you're already hooked on Glass Mask and simply want more and a different perspective on the beginning.

The Girl of a Thousand Masks follows closer to the original manga in story as well as character design. I find it a treat to watch merely because it captures the original character designs with quality animation (unlike the old and flat looking first anime series). As much as I enjoy the 2005 anime, it's nice to see this.

You can read a more thorough review on Glass Mask, 2005 version.