She is the magician of acrobatic feats, the green tomboyish member of the amazoness quartet.  She appeared first in episode 150 in BSSM SuperS.  She is blunt, to the point and stubborn.  She is on a mission to steal the golden dream mirror and periodically helps her victims before achieving her goal. She does flips, tumbles and uses a cue stick and her magic ball to achieve her goal.  In the manga she even uses a slingshot!  Very kick butt gal, who is the counterpart of Sailor Jupiter.

Later in the manga she becomes Sailor Juno, part of one of the four asteroid senshi, who have vowed to protect Chibiusa and await the day she will stand alone as a proud senshi.  Sailor Juno and the other disappear and don't come back until the ending of Stars with Eternal Chibi Moon, helping Sailor Moon against Heavy Metal Papillion. 

That's a very, quick summary, and if you are still curious about her, please visit my shrine Green Dreams, it has more details and fun things to do.  Ok, enough of the shameless plug, go join!