Haikyo Circle(2010)

Haikyo Circle

Ichinose Rei had a brilliant future as heir of Ichinose clan, until a serious accident forced him to become a girl, and his father banished him giving him a new name, Midou Maria, and turning his hateful childhood rival into the official Ichinose heir.
Maria wanted to commit suicide, but instead she ends up joining Segawa Titans, a group of highschoolers that plots against Ichinose Clan.

She found a reason to live... and now the true revenge begins!