There's a rumor in this matriarchal world that the king's dignified, low-key older sister is actually a demoness who loves tormenting handsome young boys.
It's just an unfounded rumor, but when his friend is summoned to the palace, the forbidden mage Harvey decides to risk his life and go in their place. At worst, he and the king's sister can take each other down.
It turns out Harvey was right to worry. The king's sister really is a wicked woman who enjoys using tentacles to toy with little boys until they pass out.
Luckily, Harvey is a cut above the rest. He plays the prey, then turns the tables and kills her, showing the older woman not to underestimate little boys.
Harvey had planned to make her mend her ways and then leave.
But even after being thoroughly humiliated, the king's sister still refuses to change.
Why are all the older women in this palace wicked women who have designs on him, a little boy?
Well, there's no helping it. Time to start hunting!
It's all for his friend and the many innocent young boys!
Huh? What did you say, friend? I smell delicious?
Wait, friend, why are you a girl?!