Baby Usagi is a most cheery little princess--especially when in the presence of her very own beloved Outers! Setsuna and Haruka are used to Usagi's gales of emotion, though Michiru seems fairly nonplussed. I'm sure she'll get used to it.
I feel sorry for Mamoru whenever he comes along, because now he has several 'big sisters' to deal with, and at least one of them likely will not be pleased if he teases Usagi.
Ah, I always knew Usagi loved her Outers... Now it's just official, since they're her older sisters (methinks Michi will be included in that soon enough, since as soon as she and Ruka get along, I can see them being joined at the hip)~
She is so utterly cute. And Michiru looking confused is also adorable - I wonder what will happen when she sees how fast Usagi devours any sort of sweet. Setsuna and Haruka as indulgent older sisters are brilliant. Though of course, Setsuna merely looks indulgent while Haruka looks like she wants to join Usagi in the fun.