If you ever got transported to a world what would your reaction be? Amazed, terrified, or sad. As a human on earth, transmigration is a common isekai plot and as a bookworm you have fantasies of going to another world and becoming its hero, you know it has downsides.
Like being stuck in another world for years without seeing familiar faces, you have to adapt, stay positive, and always be calm.
Wait, a city was destroyed and left by the enemy unbothered? All adults died and children survived? How? Oh. The gods of this world do not allow the deaths of children who have not reached adulthood to die in the hands of others.
Knowing that, you begin to imagine the outcome of killing a child would harbor not just hostility, but divine judgement, along with that many ideas begin to unfold, however your imagination is too big.
See those witches who lived in hiding? Yeah those monsters are the types who lure kids to eat, but is there a witch out there ugly? The answer is no, they don't eat kids and the punishment for killing a child is the curse of having an ugly face, therefore a person who hides his face is exiled from kingdoms.
Now you got the answer, suddenly while walking on the crossroads of the fallen Kingdom, kids were coming out of their houses from hiding and were looking at you curiously.
That's right, there is a loophole to this rule established by the gods, the rule is only killing so leaving them alone or selling them as slaves does not count as going against the rule.
A harsh conviction, knowing this, you can't just let these kids live on their own, so you ought to create a plan.
That's right, a way for the children of this fallen Kingdom to survive. That is, rule it as its new king, establish new order and rules to follow, become a rightful king that will protect its kingdom.
Days passed and from your hardwork and helping the kids clean the fallen Kingdom of dead bodies and dirt, you managed to gain favorability to them and from what's left of the fallen Kingdom, the former nobles son and daughters began to run their households to manage the fallen Kingdom and temporarily hired children to work for them.
Of course a war is harsh and so called war has no winner, only losers, thus all the money the fallen Kingdom have was looted minus the golds hidden.
Later on, you find out that the demon lord does not exist, magic is real but no one uses it for wars because of its catastrophical effects on the environment and highly destructive spells that can destroy a whole kingdom or a mountain using a high ranked spell. Dragons are rare so you'll never encounter one in your life, apparently they kidnapped princesses too but don't kill them, but marry them out of their kingdoms back.
Sighing, your imagination of hero saving the princess from the demon king to return to earth was gone. There's also bad news, there's no such record of magic capable of cross-world summon, all your hope of coming back to your family is cut, but would you abandon a kingdom with only children with no adults alone? Are you just gonna abandon the opportunity to raise some of your wives? What are you thinking!!
From the start, under the pretext of saving a fallen Kingdom, you pave your way to the layers of history embedding your name forever for your descendants to spread.