Yeah, it's not a whole lot of . . . anything. The rest is sound, if shallow. There isn't much to work with in Sasami-san outside of basic references.
Feels like the opening makes it clear, anyways, if you sat through the lazy mess. It shows Sasami dressed in a miko's garb while her brother marches in, and later her brother does the Haruhi dance thing before kicking off the whole chocolatey mess.
And it stops after Sasami is presented/offered to the brother (which he even states!) as a chocolate statue, and the red-sister mentions that it was the only way.