Why Did Kaguya's Bodyservant Disappear?

(spoilers aplenty below)

Before the people of the Moon arrive to retrieve Kaguya, we see her bodyservant, the chubby little girl, standing in front of Kaguya's room with a wicked looking weapon in hand, obviously ready to defend her mistress to the last. But, after the Moon people arrive, we see that she has left her post and disappeared. Then, as Kaguya prepares to leave, the children of the village led by the bodyservant are marching and singing the "Birds, bugs, beasts ..." song in unison.

So did the Moon people put a spell on the children that made them forget about "defending" Kaguya (like they did when they put the archers and soldiers to sleep)? Is the purpose of the march grounded in some Japanese tradition? Is there any significance to the little girl being the one to lead them instead of staying at her post to defend Kaguya?