I know ecchi is in the tags, but honestly this is one of the tamest and most reasonable representations of a super perverted girl I've ever seen in Japanese fiction. It's a kind of perv-panderingless (sorry, "fan-serviceless") type of ecchi that really makes me respect the author.
Getting off my high horse for a moment, aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa these two are so cute what in the goddamn