Well, at least this manga acknowledged that "adventurer" is a shit carreer only meant for muscleheads who are too stupid to get a proper job with a future and stable income.
And so economic knowledge has led to the downfall of humanity's last hope.
Many demon historians in later years praise a certain demon lord and his wife for their ability to completely crush humanity's will to fight.
If she is recognized as the heir and the demon lord dies....
Will she kill herself to fulfill her responsibilities as the hero? XD
Or will she consider her mission fulfilled and live as the new demon lord?