The Demon King from the Land of Chaos and Disorder shouldn't be so foolish, should he?
To become a Demon King merely signifies eligibility to contend with their Royal Family.
Surely one doesn't truly believe that, upon becoming a Demon King, they can provocatively challenge the Royal Family without any restraint?
Demon Suman crossed her arms and walked in front of Lance, "Demon King, if you wish to demonstrate your martial prowess, I can entertain you. It would be nice to savor the pleasure of punishing a Demon King, and I happen to have a certain interest in Demon Kings."
In the Demon King City, saying such things in front of the Demon Princess of their Royal Family was an obvious provocation towards her.
The Princess has been extremely kind to her; how could she not stand up for her own Princess at this time without failing to live up to her Princess?