It's not made entirely clear in The Tale of Genji whether Lady Koki-den is the Emperor's wife or simply one of his favorite mistresses; either way, she is enormously well-connected in the court. She wields power and influence in the imperial court, but her defining character trait is jealousy. She protects her own interests, as well as those of her son, carefully and is a ruthless combatant in court politics. Although the novel seldom provides a clear sense of the political workings of the court, Lady Koki-den reveals herself to be a power broker, especially once her son ascends to the throne.  

Lady Koki-den is one of Genji’s chief antagonists in the novel. In her jealousy, she is compared to the Lady of Rojukō. But where the latter woman, who seems to be responsible for the spirit possession of both Yūgao and Lady Aoi, comes to see jealousy as a danger, Lady Koki-den sees no reason for restraint, even when her son, the Emperor, countermands her orders.