Another Love Song at first focuses on Chise's early days as the ultimate weapon, and follows her through just past the halfway mark of the actual series. Scenes from the series are intercut throughout, just so you know where you are in the series when all this is happening, and it's a real help. It also fills in some details that were missing in the series, so it was a nice touch. I still would've liked them to explain the anime ending, though.
Added into all this is Lt. Colonel Mizuki, Chise's predecessor, who's being replaced by Chise, and is more or less her polar opposite. She also shares a mind link with Chise. So this means that not only do we get to watch her lose her humanity bit by bit and see its effects even more than in the series, we get to see how it happens mentally, and through the eyes of someone who's gone through it, and is only just starting to realize what's been done to her. You also get to see how utterly heartless the top brass are with regard to these girls. And it's absolutely depressing and heartbreaking, to watch all this, and it really kicks into high gear in the second episode of the OVA.
The other love song of the title, which is between Mizuki and Tetsu, really takes a back seat to all of the former. But it's a nice touch, on the side.
The art isn't really all that different from the series at all, and neither is the music -- although they do have a new song that plays over the credits, and it's a nice little song.
Now, excuse me, I'm going to go slit my wrists.
