Let's start this off with the glaring problem most readers will have. There is a lot of rape in this. Like an absurd amount of rape and sexual violence. It's not even really well done or given a great reason. It's just the enemy of all living things, the deadmell, just murder men and rape women. They can't procreate, they just rape for rapes sake. Now as of chapter 32 we got a reason. It's not a good reason, but like most things in this story its there. Decent amount of netori as well (Not NTR). Mostly done by the MC cucking others. Just an FYI the female family members are not part of any of the sexual stuff so far as of chapter 32. There is also concensual sex. It's not really that great either but it's there. This manga doesn't show nipples even during the sex scenes, its much closer to ecchi in that sense. Especially with some of the outfits the girls wear.
I originally found it hard to pinpoint major problems in this manga, and the art is still to this day really nice. I was reading monthly and enjoying it until chapter 18, about midway through the 2nd arc, Then I stopped reading for a little over a year. I couldn't give a reason why it just seemed like it got much worse. When I came back it all sort of clicked and I started noticing glaring plotholes with the charcaters and even the MC. Despite what the title, description, and the whole concept of a familia and how they fight, this is the kind of story where everyone else is basically useless or barely functional other than the MC. The main female family are leagues better than almost everyone in the world they go to but in the end they all end up needing the MC.
A lot of the MC's "plans" really rely on a whole bunch of coincidences, luck, and random ass pulls of his sheer insane OPness and plot armor to really even work in the first place, let alone if you actually think about it all and see how bad it all is.
SPOILERS FROM HERE: Also some heavy bitching about the writing, feel free to stop reading here.
I don't remember any issues from the opening arc, but I haven't read that in over a year as of writing this. So let's talk about the issues in the second and third arc.
Second Arc time. So, plan or not, they walk into esentially a no magic zone around daba. Despite our MC being physically weak and a mage. He could have died easily, the sister could have died. Grand scheme or not, so much has to go right for the opening to not result in death or loss. The sister gets captured, and only by the self sacrifice of the female servant/friend does the sister not get raped endlessly for days on end by the Daba king (like the servent/frriend does) or any of the princes. Then the whole plan for the tournament requires all of the princes and princess to not only just completely fall for his scam/go with it but also that no one actively went against his plan or ratted him out to the king or each other. All of this also requires that the king is so ungodly arrogant that he takes his time and doesn't rape MC's sister right away and lets all of MC's plans just go forward cause he was so confident in his strength. As well as the fact that the sister doesn't lose/die/lose a limb sometime during the tournament. Which even if you think shouldn't happen, could have still happened with a single small mis-step during the fighting. That's without any of the smaller issues that aren't a big deal. Now, most of these things can be excused as luck or coincidence in my opinion and aren't themselves bad. But when it all ends with him basically saying this was all my plan all along and you all were dancing to my tune its like cmon man thats not even reasonable. If that applied only midway then it's still garbage because he took such insane risks at the start with no basis for them other than we are the main characters so we are safe logic.
The third arc basically creates a new problem from the 2nd arc. The little sister who he had watch him to she could see how trustworthy he was by telling her to keep watch over him so he couldn't do bad things, has now decided to stay true to that and follow him to his next adventure. Despite her being useless outside her brain. Think book smart but zero common sense or street smarts. She, at a near constant pace, makes poor decisions. Like almost everytime she is left to her own devices she makes a poor or abjectly bad decision. Now you might be thinking yea, she's a 12 year old, genius or not, and that is true, but god its annoying. Don't go out of your way to overly highlight her like that. It just takes away from the character and their natural growth and makes it all feel forced if any meaningful change occurs. She is also under the illusion the MC wants her to stop him from doing bad stuff, he doesn't he just needed to say that for the previous arc, and that he needs her help, he absolutely doesn't other than for making use of her brain every now and than or as a distraction. After she has failed at every turn she is told by one of the MC's spirirts that he needs her help or he could die. None of this is true and it's all bait. So the only learning and growth she potentially got is all just an illusion for her even if she doesn't realize it. Which just cheapens her growth even more.
Then we get hit with this was all just my magical plan once again and everyone was simply doing as he wanted. Let's talk about the fact that everything in this arc goes sideways almost entirely because of the little sisters bad decisions. So he planned for it and never thought, hey lets let this be a good learning moment so she can grow as a person cause she is after all just a child. Instead its more let the filth of the world ruin her heart so she turns against it. Which then he and the family shows up and washes away any of this sentiment? I don't really understand why it's all so roundabout to make it seem like a giant master plan. Granted the arc isn't done yet but it seems like all that's left is netori'ing?(How do you even spell that) the queen and getting her pregnant.
Lastly, the MC has some glaring holes outside of plot armor by the third arc. I only bring this up because I see people talk as if the MC is the only good part of this story. So we are told, granted some leeway for translation error, that he sacrificed what it means to be a human for the 3 spirit kings to join him. So lets speculate about what that could be. The obvious answer would be free will and a conscious mind as only humans possess this. Well can't be that or the story wouldn't go forward. So it has to be either emotions or a soul if I had to guess. But based on how he acts in arc 3. The emotions don't make sense as he chose, either cause of the grand plan or spur of the moment change, to not sacrifice the two woman he slept with in this country to beat the clones and not get captured. And what does sacrificing a soul even matter for the story. With emotions out it just comes off as he sacrificed nothing or some random thing in the background that doesn't have major impact to him so far for everything. So why even bring it up this early if thats all we get and it doesn't seem we will get any clarification soon? Was better without knowing because it just weakens the concept around this MC and his OP strength. With monthly releases we may not even get it addressed for another year.
As an example they could have had the MC have no emotions but still be able to sleep with the woman and netori the other men because it advanced his goals logically. They could have had him still be cold and dark/evil while still understanding the importance of his families trust and well being seeing how strong they are against the deadmell. Just as an example of how they could have taken the vagueness of the MC's statement and built upon it or incorporated it into the story already.