Warning! Spoiler alert!
Story
This particular episode takes place after the events of season 1 and sees Yuuichirou and friends attempt to rescue a little girl who has been kidnapped by a vampire. Here's the thing, though: the vampire took the girl, not to feed off her, but to protect her because he sees her as replacement for his dead sister. Now, it's a race against time for Yuu and his friends to rescue the girls before the vampires can reach the traitor.
Without the larger story of the first season, on its own, this OVA is actually pretty good. I know that these kinds of episodes are just one-off stories that don't hold strict continuity with the greater narrative, but that allows viewers to enjoy small adventures with the characters without having to worry about continuity. (7/8)
Characters
One of my biggest criticisms against the first season is that Yuu was too focused in his quest for revenge and he doesn't really become heroic till the second half of the season, so it's good to see that the OVA features more of the nobler and more sympathetic Yuu, instead of being a angry, revenge-driven jerk.
I also enjoyed the introduction of a sympathetic vampire in the form of Shahar. Aside from Mikaela, he seems to be the only sympathetic vampire in the series. The OVA is pretty good at getting you to feel sorry for him. His vampire status damns him and his guilt of drinking his sister's blood damns him. Watching a vampire get attached to a human must have been a sobering experience for Yuu, just like watching Mikaela alive after all those years. Hopefully, this will lead towards more development for Yuu. (8/10)
Art
The visual quality was great. Everything, from the character designs to the action scenes, looked amazing. Overall, there wasn't much to screw up here. (8/10)
Sound
Praise should be given to the voice actors for their performances. Miyu Irino does a great job as Yuu. Also, I admit I'm not the biggest fan of Yuki Kaji, but his performance as the tragic Shahar was amazing. The supporting actors also do wonders with their material and do a fine job at bringing their characters to life. (8/10)
Overall
In closing here, the OVA was great. Sure, you don't need to watch it to understand the greater story of Seraph of the End but it's still enjoyable because the lack of greater continuity allows you to enjoy it as a standalone story. (8/10)
