Tsubaki Yayoi is a reformed heroine from Blazblue universe.
It seems that her mind is erased and is fallen to the dark side again by an unknown villain,who recruited her,George Washington and Mundus as The Trio of Terror.
Tsubaki and the other two will show in Maka's Storyline as one of the main antagonist alongside Ra's Al Ghul.
Tsubaki has been reformed countless times.