I've just watched the OVA and I really liked it, and I heard there was an original manga out (on which the OVA was based). What I don't know however - is how much of the story of the manga was put in the OVA.
Is there a lot of story in the manga that isn't in the anime? I'd like more of this story but I don't know if I want to buy a manga if it is pretty much the same as the anime OVA...