J.C. Staff did a great job with introducing Satsuriku no Tenshi, cleverly setting up the protagonists Zack and Rachel as well as a horror/mystery atmosphere. Many questions such as who Rachel and Zack were, where they were trapped in, and why they were trapped in the strange building were all well introduced in the first episode. If J.C. Staff had continued this quality of production, this show would have been amazing.
Except they didn't.
Just from the 2nd episode much of the atmosphere that J.C. Staff so nicely set up was almost nonexistent, as if it was completely ignored or wasn't even there in the first place. The horror feeling is gone, and the mystery just felt so lackluster. But it was only the second episode, and there was still a lot of hope remaining. Sadly, the story never picked up from this devastating injury; overtime almost everyone that was set up from the first episode is gone, no horror or mystery, as if it was entirely a new anime.
Now Satsuriku no Tenshi tried to compensate for its poor plot with good characters which can work, but in order for this to work there needs to be great character development, background or backstory, and depth.
Except there really wasn't.
J.C. Staff tried very hard to create 2 great characters, Zack and Rachel, as they worked together to defeat the floor "bosses" and reach the top. And they both developed overtime, but the reasons why were very confusing. There was not really much to explain about the reasons behind their developments, their absolute loyalty to each other(other than their oath), and who they truly were as characters. It was very confusing, being thrown Rachel's ideals of God and Zack's backstory of why he became such a murderous man. J.C. Staff introduced these factors thinking we'd understand or relate to the characters, but it only made things worse.
The art is one of the only redeeming factors of the show, it nicely fits the "supposed" atmosphere of the anime and can be considered pretty high quality. The soundtrack is also pretty good, especially the ending song.
I cannot stress enough how important characters or plot or both are to the overall story. Art and soundtrack are nice, they enhance the experience but they alone are barely enough to keep a show together. Art and sound are rather benefits, and to fully enjoy a series, there needs to be either good characters or good plot, or if possible, both. Satsuriku no Tenshi could not continue with their great set up in the first episode, and when they tried to compensate with better characters but failing to do so too, it ultimately just fell and became one of the season's greatest letdowns.
