Owari no Seraph: Kyuuketsuki Shahar

This is a very good ova. In most animes the ova will involve the characters just messing around at home or at the beach or at the hot springs, etc. But this one actually has a story, and a fleshed out one at that. The studio also does a good job at fitting the ova in-between the two seasons, even though they made this after the second season concluded. The only drawback I found, was a few little inconsistencies with the characters' personalities, but that can almost be expected in ovas. The sound and music was just as good as the main story, so you ... won't be too disappointed there. If you want to see more of Owari no Seraph after finishing the main story, this is for you, as it adds more action and a good mini-story. All in all, it deserves a 9.5 or higher.