Every revenge story has to deal with difficult questions: "Is vengeance justified?", "How many moral lines can one cross before they become as evil as his enemies?", "Would a person being avenged want all this bloodshed in their name?". Hametsu no Oukoku is unique in sense that it answers these questions very early on by making its protagonist an irredeemable monster getting off from gunning down innocent women and children from the get go.
With this shocking opening to draw your attention, I want to make one thing clear - this story is a slaughter festival about one man natural disaster willing to betray everyone just to avenge his master. It is also a story about somebody so monstrous that he had literally rejected the very possibility of bringing his master to life. Without spoiling the actual events, MC is a bloodthirsty psycho who actually decides to become exactly as evil as his enemies, right down to butchering innocent children. In a story of the war between genocidal empire and one man genocide machine there are no actually moral position.
The first 13 chapters have shown us enough of protagonist's evil that the literally genocidal empire seems like a viable moral alternative, simply because their goal of magic free, human controlled world is so much less bloodthirsty than MC's goal of causing humanity's extinction. Reading this story feels like exactly like reading a story about Nazi fighting against Cthulhu. Both sides are irredeemable monsters casually butchering innocents, but one side at least doesn't want to eliminate the whole mankind.
As for the dark elements, the series is absurdly tasteless in its use of shock content, mostly sexual violence. Look, I get that some stories are dark, but shoving random rape and gore just for shock value is genuinely bad taste. I actually don't have much more to say about it than calling it out for being bad taste and serving no real purpose beside making readers wish for empire's destruction enough to ignore the fact that MC is literally butchering women and children while crying from joy.
As for the action sequences, they are beautifully drawn but feel awfully empty. The series fails to provide the framework for the story beyond "grand magic cool, power armors cooler". All the vivid details, all the grand choreography and all the potentially cool elements are negated by the fact that for most of the time we just have people throwing unexplained attacks at one another. It feels like two kids making up super moves while playing with action figurines, just with more gore and edge than usual.
Overall, this story is very disappointing and leaves me with a bad aftertaste. It's a solid 1/10 review.