Animeverse Slayer!

Winding back time.

Leo was in pursuit of Muzan when he was stopped by a peculiar demon. Before he could react he was trapped by Upper Moon Four's Demon Art.

Looking around he found himself in a well lit room. However there were no doors, just a vast space blocked off in every direction.

He turned his sight towards his opponent. A frown climbed onto his face, however soon it turned into shock and rage.

"What the f*ck did you do!?"

His voice was tinted with cold murderous intent as he spoke.

The demon with eyes and limbs all over it's body let out a disgusting laughter.

"Leo Heart, how do you like my gift?"

Leo was startled when he heard that voice.

"Muzan?"

"Hehe, good guess. However I am just a part of his conscience."

Leo didn't bother to ask further and rushed forward. His red sword cut the demon in half before separating it's head from it's body.

However Leo didn't sheath his sword. He took a step back and watched.

The demon's flesh started to squirm and reached out for the other half. It merged into it's original form in an instant.

A hearty laughter escaped from it's innumerable mouths, "Haha, you can't kill me. This demon was created for the sole purpose of killing you."

Leo's face looked cold like an ice tundra, "For that purpose, how many did you kill?"

The demon smirked, it's body filled with faces painted a horrifying sight, "20 thousand. No, 30 thousand or was it 50 thousand. Who knows, would you count how many ants you step on?"

Leo nodded, "You wouldn't."

He took a step forward and struck again. This time he sliced the demon's body into countless pieces of flesh.

However a second later the demon again merged back into it's original form.

"I told you, it's useless."

Leo wasn't interested in a deep conversation. His sword gleamed brightly as he striked again. This time the demon struck back.

Countless arms grew out of it's body and smashed towards Leo.

The rain of fists didn't bother Leo.

An Azure Dragon silhouette covered his body, he swiftly moved past the incoming rain of fists.

Blood splashed. The arms proved useless infront of Leo's overbearing attack. They fell one by one.

He reached his goal and cut off the demon's head. A bloody line formed from it's head to toe as it broke in half.

Leo raised his sword.

His domain was working at full power. A White Tiger came into existence when he raised his sword.

He slammed his sword down. With a roar the White Tiger pounced on the demon and struck with it's menacing claw.

Leo drew out his sword and waited.

When the dust cleared he saw the demon laying down with it's body shredded to pieces. But just like before it merged back into a whole again.

He was sure he had killed whatever was infront of him. But this demon kept coming back to life. He was starting to feel annoyed.

Is it really impossible?

"What? Not attacking?"

When the last piece of flesh merged with it the demon stared at Leo and grinned.

Leo focused. He disappeared and struck the demon again.

Leo's attack was met by the demon with one of it's own. However against an immensely powerful opponent like Leo it could only slightly pause him.

When he 'killed' the demon Leo fully focused using his spiritual sense.

I don't believe evil like you will be immortal!

Under his overbearing spiritual sense Leo saw everything clearly. However he frowned. There was nothing wrong.

How is this possible? It's body is fine even after dying four times?

Just as he was about to pull back his spiritual sense he saw the demon's spirit.

It had a myriad of colours with lines criss-crossing all over it. It looked like a piece of cloth with countless patches.

When he first saw the demon he already understood what it was. This wasn't a single being but a collection of tens of thousands of lives.

Muzan in his fear of Leo tried to create a monster out of tens of thousands of people. He tried merging them into one whole being and the result was this disgusting demon.

Leo focused on the demon's spirit. He saw a patch smaller than a grain of sand vanish. Right after, the other patches filled the vacant space.

The demon again came back to life.

Leo finally understood.

He stared at the demon who just became a whole again and said, "You are substituting your life with the humans you merged with."

The demon was startled for a second, however it soon relaxed, "So you found out, so what? What can you do?"

The demon smirked, "Each time you 'kill' me you are also killing one of your kind. How does it feel? Does it hurt?"

Leo still maintained his icy expression. He disappeared like a gust of wind and reappeared right beside the demon.

He cut it's body into pieces and pierced his sword into it's heart.

A faint light glimmered on his blade. It was weak and only had the thickness of a paper, however it was there.

The demon suddenly felt an intense pain assault it's brain.

Aahh!

Leo stared into it's eyes, "How does it feel? Of course I feel like shit!"

He took back his sword and cut off it's head. The demon died, another patch on it's soul disappeared and it came back to life again.

The demon just came back to life when Leo crashed into it like a meteor.

"Haha, you can't kill me!"

Leo cut him down again and the demon came back to life again.

Once...

Twice...

Thrice...

Leo lost count of how many times he 'killed' the demon. However he didn't stop.

If he can't kill him once then he will kill him twice. If that doesn't work then he will try a hundred times, a thousand times!

No matter how many swings it takes. He will end this demon and put those spirits to rest!