S1·E10 Battle at the Mysterious Ancient Capital

Riku's grandpa finally wakes up, and he tells Riku to go to the Ten-ryuu Taihaku Shrine in Kyoto. He eventually finds the Taihaku shrine and meets a young girl who seems to be the only person working at the shrine. She begins Riku's "training," but then a Chi-ryuu Toujinshi named Chihaya busts in and summons his Shikigami, Kaede no Kurenai. When they are about to finish off Riku and Kogenta, the girl reveals herself as Nazuna, a Toujinshi of the Ten-ryuu, and summons her Shikigami, Hiiragi no Horin.