First off, it was supposed to be a complete, 13 episode series, but they messed up in production, and still had 4 episodes left before the story ended. So they're like hey, its OVA. Therefore, when purchasing this series, I had to buy the first 13 episodes as the official series, and the 4 episode "OVA" as a separate packages. It is, more or less, a cashgrab.
But the series itself is eeeeeeeeeeeeeeeeeeeeeeeeeeehhhhhhhhhhhhhh... The first episode is really just full of shit, and it obviously turned away most viewers who were interested in the show. I stopped watching it for about a week and ended up marathoning the rest later.
After the first two episodes, shit. gets. real. It really takes a turn for the better, and becomes something that could be actually deep and interesting. It goes from "Hey, body switching is to damn cool, and boobs m8" to Feels 4 Dayz, in the best comeback of a anime that I have seen. Then after 4 episodes of greatness, the first arc comes to a close. It then gets subpar for a little, only to make a full recovery in the "OVA". The only problem is you have to watch the mediocre part of it to actually get the "OVA", so it's not worth your time.
If you have a moderate interest, watch the first arc at least. If you are feeling thirsty for more after finishing the first arc, watch more. That is my certified recommendation.
