What I expected going was an edgy isekai to waste some time, and i'm satisfied from that perspective, but multiple aspects of the story bother me.
The premise of the story is about how an experienced assassin, after outliving his usefulness and being backstabbed, gets isekai'd to kill the hero because the hero will go berserk and mess the world up after beating the demon king.
First of all, as in Mushoku tensai, i'm not sure how to feel about an adult(mentally, at least) explicitly grooming some kids. And this manga is much closer to actual grooming: The MC explicitly takes advantage of the mental vulnerability of those kids to make them dependent on him. Sure, he wants them as tools to help with his assassination, but even this paints him in a negative light. This undermines any attempt the manga has of developing his character to being more 'loving' and 'family-oriented'. The scenes where he reflects on how he feels more inclined to protect his family or whatever feel undeserved and thus shallow.
The side characters in the 13 available chapters are there chiefly to make the main character look cool. The majority of the dialogue coming out of the girls' mouth is about how they like the main character. Especially for the maid girl, the majority of her scenes are either fanservice or blushing and stuttering about liking the MC. The MC is somewhat interesting in his lazor-focus on assassination and the task at hand, but this also means that he's quite one-dimensional.
The manga also pushes a weird economic/political message. I mean, we already have the romanticisation of monarchism as a genre convention, but that's not all that is here. Try this scenario on for a size: One of the girls the MC saves was the daughter of a merchant who was murdered and had his buisness taken over, so she is left on the streets. However, she is savvy, and despite having no material standing or connections whatsoever, somehow organizes the other orphans and starts a buisness! But alas, as she is going to be successful, the government invests into social programs, so that kids are taken off the streets and put into orphanages, run by bandits looking to profit from the money they will receive from the government.
This rubs me the wrong way, because it's frankly a whole lot of rubbish: An orphan on the streets isn't going to start an entrepreneurial buisness, they are probably going to get kidnapped and trafficked. Having a social net for homeless kids is 100% better than leaving them to be saved 'by the invisible hand of the free market'. Now, you may say that i'm stretching it with this critique based on one example, but this is NOT the only time the manga does something like this in 13 chapters.
The 'skills' system is only called that by genre convention, because it has little to do with the rigorous mapping out of different possible skill trees and having creativity come from the combinations of limited possibilities which comes to my mind. We become aware of skills when someone uses them and everyone has unique skills, so it's pretty much just superpowers. The magic system is more interesting with some aspects which have yet to be revealed, and the majority of cool stuff and inventiveness in combat comes from magic. As isekai rules command, our protagonist controls ALL types of magic. I can't remember the last isekai where the MC couldn't do this.
The art is on the decent side.
If you like the genre, op protagonists whom all the girl love, and want an edgy twist on it, give it a try. The technicality of the magic and how the MC often incorporates his knowledge from his past life to solve problems with the mentality of the assassin is somewhat fun. Also, try 'the beginning after the end' for pretty much the same plot setup except the cool assassin stuff, but with somewhat more thoughtful writing.
If you wanted an isekai with an experienced/mature MC which would play with/break genre conventions, this ain't it. Try 'Ninkyou Tensei: Isekai no Yakuza Hime' instead(yakuza reincarnation).
