Sasha is one of the 10,000 players who were trapped in the death game Sword Art Online. Sasha takes care of the younger players of SAO in Starting City. After being freed from SAO, she eventually joins ALO.
Chronology
Aincrad Arc
Morning Dew Girl
She resides in the first floor and takes care of the younger players, since most of them fell into psychological trauma. She lives with them in a church, where they hide from the members of the Army.
Fairy Dance Arc
At the end of the Fairy Dance arc, she attended the SAO clearing party along with other SAO survivors. In episode 25 of the anime, Sasha is shown as a Puca flying with the rest of the SAO survivors to the new Aincrad.