This is the story of when Miura attempted to mimic Western political correctness as cringeworth as you can imagine an atempt like this can be. Besides all the positive reviews which I believe are based on just being fan of Miura's work (more specifically, Berserk), there are plenty of issues in this manga that need to be adressed.
There is no story to be qualified, it's a political NPC commentary in manga format sumed with some strange form of Buddhist morality. A human warrior and a kind of android loli who follows him are captured by an humanoid tribe (Blacks are some bugs) who suffer from the evil of "Human Imperialism", some type of victimization NPC rhetoric. Miura makes some one-sided, propaganda-like demonization of Western civilization and all tribal community is super good and innocent (as if tribes never plundered, raped and enslaved one-another as history proves, just muh evil civilized humans). There's no interesting, morally grayer interpretation of humankind here, for example how it happens in Attack on Titan, just "Black vs White", as the worst pun it may sound.
Now this is not even the worst part. Let's say you're totally ok with the politically-morally cringy aspect of it and will read for the characters and the plot.
There's no conclusion. The "ending" is some Gainax Ending that is the terror of any anime/manga fans who had experiences with bad endings, and can cause chills down the spine of Berserk fans if you stop to think that Miura could some day do this to Berserk. Remember the "black and white" mentioned above?
"Ok you fucked this people over but my Loli has the power of friendship and peepee to wash everything you've done as if nothing happened. The End."
Who needs to develop a reason for an ending when you can simply wash away all the negative parts in a convenient holier than thou false moralism and Deus ex machina.
Miura was probably worried of how much depth and political incorrectness he has put in the Conviction Arc of Berserk, and seems to have attempted to repent his Japanese imperialist fash manliness in this weird volume.
They're cute. The main characters are chubby versions of Roderick, ep. 252, and Schierke, ep. 184 (or Chitchi, ep. 329), from Berserk. Their interaction sums up in making pee jokes and being the saviors the "oppressed minority bugs", "we are your White saviours" Aids Skrillex type.
The art style follows the Fantasia Arc of Berserk without great improvements. Even if it was the best of Miura's art style, it would not save the fishy nature of this manga, and you'll feel like the art is too good for a story so bad.
People who read it and gave a blind eye for its defects (or at least tried to ignore the political cringe) are probably desperate for more Berserk chapters or just more Miura's creations in general. Someone who enjoys the man's work, specially Berserk for what it is, and see through this manga will hope Miura never ever do this to his Magnum Opus.