Sixteen-year-old Raias is Rufus' younger brother. He is also playable (he uses a gun in battle), and is recruited by Rufus to escort Meruru. He seems a bit envious, though, about his older brother's preoccupation with Meruru and agrees to help him, hoping to win some of his admiration.
Gust also shared a couple more videos today. Atelier Meruru's prologue is over 4 minutes long, and tells a little bit of the background story.
Here's some gameplay footage, mostly of Meruru running around. That girl's got legs.
Atelier Meruru will be released in Japan on June 23rd.