@Tsuki09 True, but considering that :
-1 : The villainess knew everything about the Demon King and was already interested in him (Since she says she always wanted to do his romance road, we can even consider she did it several times. She knows a lot abour him after all)
-2 : The Demon Kind has...
@Moffle She assumes it because she get paid, meaning that they confirmed the information was true. Plus, she says there is some magic stones in blacktown if I remember right. It's knowledge from her previous life.