Kita no Kurohime

Sei's older sister whom Sei greatly respects. Kotaro commented that both Sei and her do not like to talk much. The Princess has lived for a very long time and is also a descendant of the chaotic bloodline. She resides in the Sacred Precinct with Crow, where Jiro and Kotaro previously stayed at. She was sad to see him go, so Kotaro consoled her by saying he will write to her when he reaches the Special Zone. Despite her quiet demeanor, she apparently has a short temper and while she enjoys Kotaro's company, if Kotaro does something that angers her, the Dark Princess does not hesitate to hurt him. Her powers are great enough to warp and change the very weather surrounding her. -wikipedia