She is introduced in ep.5 as the greatest strategist of Mino who is also an onmyoji, she uses a Shikigami, which she named "Zenki", that looks like a grown up man as her double since she is too shy and prefers to hide in the shadows. The reason for her being a recluse is because she was once bullied because of her talent. She was then rescued by Sagara after she reveals herself to Yoshitatsu who had her uncle locked up. She pledges her loyalty to Sagara after seeing his kindness.
(Source: ANN Forum)