Kaiko is Keiki's nyokai (female youma who protects the Kirin). She looks like a woman with feathered wings, fur, and bird feet.

In her first appearance, Kaiko is summoned by Keiki when he and Youko Nakajima are trapped on the roof of her school by kochou. Kaiko carries the Suiguutou for Youko to wield against the monsters, but Youko's lack of ability to wield the sword and the pressing need to escape results in the group fleeing to the local seashore.

After Youko defeats their pursuers, Keiki assigns Kaiko and Hyouki to protect and carry Youko to the Twelve Kingdoms while Keiki departs with Hankyo. Upon arriving, Kaiko and Hyouki are seperated from Youko and Jouyuu and sealed by Kourin, who has captured Keiki for her master. She is freed after Youko is reunited with Keiki and the Kirin is freed from the spell binding him.

(Source: wikia)