SPOILERS AHEAD
The show started very well. Despite of the amount of people comparing it with AoT, the first seemed that this show would be a blast, and also would be nothing like AoT. However, after 3 episodes, this show became a trainwreck.
The plot is almost nonsensical. Kabaneris wear tight necklaces that for some reason don't asphyxiate them, Mumei gets transformed to Kabaneri by Biba just because of silly reasons, Biba wants to transform everybody into Kabane because of silly reasons etc.
Furthermore, there are disturbing plot holes. Katanas, that are fragile swords, somehow could pierce a Kabane heart. In contrast to that, in the following episode, Ikoma had to build a Kabane-based Katana for the samurai guy because a normal one can't pierce the zombie heart!!!!!! WHAT????
The main problem with the show is that the plot isn't straightfoward. To be exact, the plot is almost inexistent. It's a train trip with friends. Sometimes the train gets attacked by the zombies and BOOM, we get nice action scenes and it's over. Later on, they meet a group of anarchist Kabane exterminators that in the end will try to kill everybody. And what happened in the last episode? Suddenly Ikoma becomes Ouma Shu and started to have Guilty Crown-ish powers. I was like "WHAT THE HELL?"
Also, the plot conveniences and the idiotic actions that some characters take in some chapters really annoys me, like when the purple-haired girl cuts herself wasting a lot of blood that could have be given to the Kabaneris instead of being wasted.
The characters were totally undeveloped. The only one that we could say that had a decent development was Mumei.
On the other hand, the ost and animation saved the day. They have Sawano, EGOIST and Aimer. This is a dream team! The art was very beautiful. That steampunk vibe was very nice too. KotIF is one of the best looking anime that I have ever watched, only losing to the Fate series (ufot. vers.).
To sum up, the anime wasn't very original, but had some potential that wasn't well explored. If you want to watch this, expect nothing more than a very nice ost and action scenes, because the plot is utterly trash
