The protagonist is slowly bleeding to death after an accident, and someone decides to pull out a phone to record it. And honestly, that's how it works in the 2020's. Recording something "interesting" is like a reflex for people. Who cares if the dying person dislikes being recorded? He's gonna be dead by the time you upload the video.
The author took the "death and resurrection" beginning of an isekai story and turned it into a mirror of the ugly reality we all live in today.
Story: It's not a very original story. A fantasy world with dungeons, adventurers and levels. Slave x Protagonist. The typical things are all here. But the world building is done in such a way that it has a nice feel to it. It feels similar to "Grimgar". A very serious world, set up to be unforgiving and make people struggle for survival. Early volumes has no actual plot. It's simply about trying to stay alive... I like fantasy, and the author took a mainstream theme to make it interesting enough for me to want to read more. It's nothing new and yet it stands out from the rest. I like it, because unlike most isekai stories it's not too fast moving. We have time to start liking the characters and just learn more about the world.
Art: I would say the art is surprisingly normal. It's good at adapting for the feeling of the story, the more serious scenes can look disturbing and gross, and then during the more slice-of-life scenes the art is cute and simple. Even then, the art is never especially good. Shades is the biggest down side, it looks a bit too monotone at times.
Characters: The protagonist and his slave girl has the typical mentality. "I want world peace and for everyone to be happy." And even though I don't like those type of Naruto-esque characters, I still enjoy these two. There's nothing to really complain about, except for the age difference. The girl is 9 years old, the protagonist is 17. As long as they stay just friends, it's a cute pair of characters. It is easy to like them, because the story gives a lot of details and spends the time to make them likable. The best characteristic is that (just like Naruto) the protagonist sometimes becomes crazy and loses his mind, sometimes leading to brutally murdering the bad guys. And that's quite nice, considering he is usually a pacifist.
Overall. I like this story. The humor is kept to a minimum, but funny scenes still pop up throughout the series. The world is really dark, but there's not too much exaggerated drama. The story has a good pacing and it's a very open story, there's is no "goal" to go after, it's just about survival. The less enjoyable things are the use of flashbacks, and the fact that we have a possible pedophile as a protagonist. As long as the manga stays away from romance between the main characters, it's a good manga with a rarely seen darkness.