My Overprotective Dad Has Gone Dark

My handsome, overpowered dad, who only ever cared about me, ate something strange and turned into the Demon King.
He used to be the sweetest, most doting father, but now he’s the final boss?!
Because of this, my dad is fated to be killed by the male lead, and I’m destined to die lonely while mourning him.
At that moment, I returned to the past and realized that this world is actually a game!
I couldn’t prevent my dad’s descent into darkness, but no matter what, I must turn him back into his original self.
If I succeed, I can get my loving dad back, right?
For now, I need to get close to the male lead, who’s destined to kill my father…!
So, I became a Holy Knight and even managed to be adopted as the ward of the Pluto Ducal House—the male lead’s family.
…The problem is, I’ve become way too strong.
As long as I get along with the male lead, my dad might avoid being labeled as the Demon King.
“But that’s strange.”
“…What is?”
“Your lips… they’re heart-shaped.”
“W-what? Don’t look at my lips!”
At that, the male lead tried to avoid my hand and ended up rolling under the bed.
“Ahhh!”
“…?”
He’s supposed to be the strongest person who’ll one day kill my dad,
but for now, the male lead is just too cute.