This is what happens when you are too carefree in your surroundings. He said in the previous chapter that he needed to grind for a level-up, but he only did it for a day, and the rest is just playing and fooling around with his harem. He's a demon lord, and he's living with the supreme dragon. It's common sense that there is always a danger there, yet all he does in every chapter is just chilling in his house...