Oh Pupa, such a weird little thing. I doubt there was a show that pissed off more people this season (following into Aku no Hana's footsteps)! The key factor to the problem is the episode runtime - just four minutes (with about two of those being taken up by the OP and ED). With this little time Studio DEEN deceided it would be a good idea to adapt a vore-themed story about a brother and a sister that was originally told in a three volume manga. Helmed by a not unexpirienced director (Tomomi Mochizuki) it leaves many questions about their true intentions. The art is not pretty, the episodes rather disconnected, the voice acting not very good and even the SFX sound rather low quality. Then there is also it's content; with cannibalism being a core theme airing them anyways but censoring the shit out of them with shadow/light-overlays... what is the point? They should have released these as OVAs but with a longer runtime or something like that. Nothing is resolved and the last episode is a flashback to when they were little kids and being all cute... It was never a good story anyways but certainly more coherent than this. Maybe they just wanted to take the piss out of some of the more energic fans obssession over little sisters or something (which 1x06 Encroach seems to hint at). If you want to watch it I'd suggest waiting for an uncensored release, it only takes you half an hour anyways.
For those looking for anything deep behind sibling relationships I'd suggest to take a look at this behind the scenes to see that Sayaka Mogi didn't have much in mind when thinking this thing up: http://www3.nhk.or.jp/nhkworld/english/tv/imagine/flv20140213_archive.html
