The Tenth Pillar. (Kimetsu No Yaiba X OC)

Of monsters and humans.

Tamayo found herself losing the battle against Muzan. Little by little, her body became a part of the father of all demons.

"You worthless woman. Just die already!" He cursed and growled.

The demon woman knew that her end was near, but her efforts were not fruitless. Muzan was desperate to find a way out of the fortress, all the Upper Moons have fallen against the demon slayers corps. He was scared.

"You will die today..." she whispered as her body got absorbed by the demon, at least, he was free.

Before the demon could move, a large group of swordsmen made their way to him. They weren't even pillars, just some stupid soldiers who thought they can do something against the mighty demon.

He morphed, his limbs became tentacles, his hair turned white and from his back another set of bladed tentacles spluttered.

That was his battle form.

Muzan wiped them with ease, a sadistic smile on his face as his sharp bladed tentacles emerged from his arms and back, with his mutated limbs he massacred the foolish soldiers.

"I shall kill all of you, humans!" He proclaimed he rushed his way out of the fortress, trying to escape from this desperate situation.

He spotted them, a big group of swordsmen made their way to him.

"DIE TRASH!" The father of all demons launched a deadly poison, enough to kill all the swordsmen, who swiftly evaded the incoming projectiles.

As the battle raged, Tanjiro lead the assault against his arch enemy. Even the Hashiras trailed the young demon slayer, unleashing his strongest techniques against him.

Sadly, they were not going anywhere. He was that strong.

Soon, the fortress trembled all of them retreated as they saw when the mighty stronghold crumbled leaving them at a deserted town.

A demon slayer crow made It's appearance  flying around all the people fighting against the white haired demon.

"CAW CAW THERE'S STILL AN HOUR AND A HALF FOR THE SUNRISE. STALL HIM!"

The demon slayers smiled, a little hope was lit. Muzan can be killed.

When the fortress dissapeared, Shinobu became stiff, they were surrounded by trees and the grass felt nice underneath them.

Hiiro couldn't move an inch. His body was nearly to It's break point. Using the bankai was a huge burden for him. The insect pillar offered her lap for him to take a rest.

"What happened?" Shinobu asked while taking a look around.

"Mitsuri and Inosuke defeated Upper Moon four. The blood demon art she possessed was the one that made possible the existence of the fortress." The raven haired boy explained, opening his eyes. "Everyone will be fighting Muzan. Damn, I need more time..."

He mumbled some curses as he clenched his fists. The two black swords rested at his side, ready to go at any time.

Shinobu's small hand stroked the silky hair of the boy. She carefully caressed his cheeks, her soft fingers drawing a line all over the boys jawline.

"You need to rest, Hiiro-kun. You fought against two Upper Moons all on your own." Her beautiful eyes turned sad "We couldn't help..."

"Stop it." He caught her small yet delicate hands with his. "We knew how strong they were."

Her amethyst eyes melt together with the golden orbs of the boy, she bent over his beloved Hiiro. Pecking his forehead with her soft lips.

"Thank you, for saving me." The grip on his hands became tighter, her eyes began to tear up again.