This OVA is a sort of take on the whole end of the world scenario in the setting of Higurashi. It's set in a parallel Hinamizawa where things took a turn for the worst.
I think this OVA hits home more the vibe of the first Higurashi season the n the second, because of the the fact that Kai didn't hit home with me as being horror the way the first season did. Also we see Rena in her creepy mode again.
A pleasant surprise for me, that I didn't notice before was the length of the OVA. The fact that it's twice as long as a typical episode lessens the con that this is, as of writing this review, the only episode in the Kaku OVAs. Furthermore, the pacing of the story is very fast, covering story that would normally fit into 4-5 standard episodes.
As a conclusion I want to say, that this is a very good OVA and I recommend it to everyone that enjoyed Higurashi no Naku Koro Ni, especially the first season.