....so...the princess is not only responsible about Funayama's death, but also for the death of who knows how many other children that died after the building's collapse when she knowingly and selfishly summoned a bunch of children to use as disposable children soldiers...
Yet the MC is allowing her to live still...the woman who has the knowledge to repeat said summoning and potentially kill even more children as a result.
And don't tell me she won't because "she thinks she's the MC's familiar", she's cunning enough to at the very least realize that her volition is still her own, if now outright that see through the MC's lies. And her end goal is still the same, raising a cheap slave army to protect her kingdoms from the neighboring empire.
Only this time around she'll be more careful while she does it and make certain to dispose of any "demon kings" directly instead of sending them to die in a forest.
Also, the "she's in command of the monster countermeasures, so she has to live" argument is equally silly, the MC could easily destroy what's left with ease and increase his army's power as a result.
But hey, the storywriter says big tits = survival.