This is one of the anime that you can call "Original".
I will keep myself from writing any big spoiler.
First of all, the most important one, the story.
At early episodes, you will see this anime as a general shounen anime with naive MC that doesn't want to kill anyone with a big dream on his heart of returning their original body back. But as the story progressed, you will see the exact differences. That is because instead of winning by being OP thanks to nakama power at the lasts second in a battle, you will often see MC either being saved by someone else or running away instead. Me, who actually expecting a generic shounen, am impressed by how good the author played the cards on their hand. Even though he seems so OP, seeing the despair in that anime makes even me realize that his OPness is only a small being compared to the climax.
The author also played the " sacrifice" and "equal exchange" thingy beautifully.
As for Art and Sound, I'm pretty impressed too. The OP and ED fits pretty well, and the BGM were played out nicely. The art animated beautifully for a 2011 anime, though in one of the fighting scene, I realize some minor things like when there are 2 people join hand fighting a single enemy, while one of them fighting the other one just stayed still for a few seconds which is weird. But that doesn't stop me from enjoying the scene.
The characters development is one of the good thing too. I thought that most of the important role might become naive after meeting MC, but surprisingly they still maintained their former personality, but I still can see the character development. Some of the example were Roy and Greed.
It's definitely something worth trying, and doesn't leave a bad impression.
