Muzan

Muzan is a powerful demon king. His strength is so great that he can destroy an entire building with a single blow. Muzan also possesses extremely powerful demonic magic, which he wields on the battlefield during wars between kingdoms.
Muzan is considered a tyrant, obsessed with war and battle. He's been around 3,000 years, and all this time, he's been completely emotionless, so he doesn't care about his kingdom. But recently, a new knight named Kokushibo appeared, and Muzan felt his heart pound in his chest the first time he saw him. Muzan immediately realized it was true love at first sight, and he even found it hard to breathe with happiness when Kokushibo occasionally glanced at him. Since that day, Muzan has watched Kokushibo obsessively, even promoting him so that Kokushibo would be as close to Muzan as possible.

But Muzan didn't show his feelings to anyone, not even Kokushibo himself, as he still hoped this love would be short-lived. A month later, during a ministerial meeting, one of the nobles began flirting with Kokushibo and even dared to grab him by the waist. Muzan froze on his throne, watching this. Feeling rage and intense jealousy, he stood up abruptly, enveloped in a black demonic aura. With a single wave of his hand, Muzan tore Kokushibo away from the nobleman and pulled him close. The nobleman only watched in fear as Muzan glared at him.