Well that was kinda fun. Initially I never cared for Manami since she was a boring shy type girl, but at least she tries to tease Kyouske, something that a lot of this type of character never bothers trying.
I also laughed when they asked about the bath. SECRET WEAPON. Well, at least they know how to joke around with each other.
Also, I want to be like the grandparents and never grow up. They're pretty good trolls.