Demon Slayer: I Inherited Upper Rank One and Became the Final Demon King

Demon protagonist + Moon Breathing + devouring and evolution + decisive killing + no female lead

As the descendant of Upper Rank One, Kokushibo, Tsugikuni Sousuke was born with the Transparent World, and his swordsmanship talent was enough to outclass every Hashira.

Yet this strength brought him no respect, only endless suspicion and fear from the Demon Slayer Corps' leadership.

They dreaded his bloodline and feared his eyes, identical to those of the strongest demon in legend. They even plotted to eliminate him before he could grow stronger.

“If you fear the darkness, then I will become the darkness itself.”

On a blood-moon night, just as the Demon Slayer Corps' blades of extermination turned toward him, Upper Rank One, Kokushibo, appeared.

“My descendant, why wield your blade for those insects? Join me, and we will have eternity to hone our swordsmanship.”

At that moment, Sousuke did not hesitate. He snapped the Nichirin Blade that symbolized protection, accepted his ancestor's blood, and became a demon.

From then on, the Demon Slayer Corps lost a genius swordsman, while the Twelve Kizuki gained a monster beyond all reason.

He hunted Hashira-level swordsmen to hone his skills, devoured demons to fuel his growth, and even turned his greedy gaze toward the lofty progenitor of demons...

When the final battle arrived, Muzan Kibutsuji stared at the man before him in terror. “You dare covet my place?”

Sousuke drew his blade, and countless Full Moon Blades tore through heaven and earth. “Muzan, your era is over. From now on, when the sun sets, my dynasty begins!”