Kaguya is the main character and the "Princess of the Choosing." She is fated to decide which World survives when the end of the universe comes.
Seeu's main role towards Kaguya is that of a protector. Although in the beginning of the series it appears that Seeu is the main antagonist, in fact he was only attempting to keep Kaguya out of Emperor Kura's hands.
Kaguya seems to be very curious about Seeu, and talks to him often. Although Seeu rarely responds, Kaguya has some sort of affection for him; however, this is most likely due to pity.
Seeu disregards Kaguya and listens to her in a vague way, but he ignores her when she suggests something that he doesn't want to do.