The Demon King Is Actually This Kind of Person!

"From now on, she will be your junior sister."

The Demon King said this to her disciples, holding a little girl by the hand.

"Master! Didn't you take on a junior sister for us just a hundred years ago?!" a certain fox-eared girl said, sounding rather huffy.

"Yes. What's wrong?" the Demon King asked, puzzled.

"What do you mean, what's wrong?! Didn't you say back then that you wouldn't take on any more disciples?!!"

PS: The first world's story takes place in Runeterra and is related to LOL.