The Mole Demon King

"Mr. Chen, you're a Demon King, yet you don't hone your skills at killing and burning, plot schemes to throw the world into chaos, or nurture ambitions to rule over all. Instead, you mingle with humans in the city, living in harmony with heroes as an adventurer... What gives?"

"A while ago, a hero led a party to conquer my dungeon. I was in his party at the time."

"Oh? And then?"

"Then, while they slept, I sang. While they ate, I spat in their food. When they argued, I egged them on. When the women bathed, I peeked. With the hero and his companions in such a terrible state of mind, they could only manage three or four tenths of their usual strength. My subordinates chopped off their heads, one by one."

"Ah! What an incredible tale!"