From the Animeraider:

Ayaka tries top be normal, but she’s got a secret – that she’s descended from a legendary line of fighters. Everyone knows she’s strong at martial arts, but she’s much stronger than she lets one. And then one day she’s attacked by someone with nearly her speed, only to be rescued by a strange boy who is stronger still. And so a battle for control over the spirits that give Ayaka her fighting skill begins…