To begin with, aside from one person in the entire story, EVERYONE is trash. Main guy: genocidal angst monster who wants vengeance because shitty people did shitty things. While I sympathize with his reasons, wanting to kill everyone is an extreme overreaction. Main girl: dumb bubblegum simp. Main guy literally threatens to kill her at least once an episode and she still follows him like a little lost puppy. Her back story that could have been interesting is just washed under the rug. Everyone hates me because of my powers? Oh well, let me just spend all of my existence screaming the main guys name and stalking him. Villain: so overly attached to her boyfriend that she'd go to another world and ruin it just to get him back. Women whose sole motivation is the man in their lives seldom make actually good villains. Side characters: Literally just bad people with bad motivations. One character in this story is actually decent, and she gets horrifically murdered in the first episode.
Then we get to the story: boy wants revenge for the murder of his mentor. Okay, we've done that before successfully in other properties. Though the boy who wants revenge doesn't usually want to kill everyone indiscriminately.... Honestly the show feels more like how much blood can we spill JUST because we can. There is an episode where people are standing in blood up to their calves. Its violence just for the sake of being violent, which I guess if that's your thing, then this is the show for you.
Overall, I will give ONE episode some actual value, but even that episode is kind of uncomfortable. One episode acknowledges the hubris of man and technology with sex robots. That is the ONLY episode in the show that might be worth something for having a decent message to it. But it feels so detached from the rest of the show that I can't even use it to boost this from anything other than a 1 Rating.
There are thousands of other anime out there. Please don't waste your time on this one.