What initially drew me to Sekai Oni was the idea of this "other world" in a reflection. I expected it to be more of a psychological story, with Azuma struggling against the abuse of her family (aunt, uncle and their sons) and those first chapters fed into my expectations of what this piece is going to be. However once the story started coming together, I realized that this is gonna be a different kind of tale. Once we meet our supervising Cheshire devil and the other unfortunate souls similar to our main protagonist, each with their unique past and struggles, it takes a strange turn.
Truth to be told, I did not care about the other characters at first, same as Azuma. I thought they will only become a casualty/emotional fuel down the road, but I am glad that I was wrong. With each chapter as we got a glimpse into their lives and motives, I grew to like them and the impact they left on the story is undeniable. Though some moments made me cringe.
The story by itself was a bit lacking. With the other half being mostly thrown upon the readers like an avalanche of new information. If it was not so rushed, I might have enjoyed it more and get a better understanding of what exactly was happening. It brought some interesting concepts to the plot, but the unwillingness to commit to them fully made me not care (e.g. "reserves").
Overall it was a harder to follow piece, with a lot of action and enjoyable quality.