The Tenth Pillar. (Kimetsu No Yaiba X OC)

Unknown Reasons

As Zangetsu cut through flesh and bone, the last demon cried his life away. The moon was slowly falling from his dark throne and the very first lights of a new day were peeking out from the horizon.

Hiiro Kojima studied the last demon he fought. That night he found a demon nest, just like Oyakata-sama requested, he killed all of them. Demons not always hunt alone, there are times when they live in groups, but not large ones. Ten demons were nothing to him, just another mission to accomplish.

"Well, let's head back." He sheathed his sword and began his journey. Hiiro felt his heart race and a growing anxiety. Shinobu and Mitsuri are waiting.

The butterfly estate was in a deep and silent peace. Aoi Kanzaki enjoyed the warm day as she did the laundry. Half of the punishment was gone in the blink of an eye.

"Monitsu! What are you doing?!" Her ocean blue eyes pinpointed the location the yelling was coming from.

She let out a sigh and then giggled. The raven haired girl was happy about the three young demon slayers that were training and going through rehabilitation.

Surely the estate has become more lively and noisy, but it's nice to have them around. The crybaby Zenitsu Agatsuma was pretty loud but he's still a nice guy. Tanjiro Kamado, he is a really nice guy, hardworker and with iron will. This young demon slayer even pushed Kanao into opening herself. Lastly, Inosuke Hashibira. A loud young boy, he raised himself in the mountains, he goes around yelling and has zero manners, but he has a sweet side of his own, even though he's rude and noisy Aoi thinks he has a charm that she really really likes.

"Oy! Monistu, you're doing it wrong!" She laughed cutely and continued with the task.

"I didn't know the loud ones were your type" the young nurse jumped when the night pillar addressed with a calm voice.

Her ocean blue eyes were locked on the young man, he was healthy, not a single scratch on his body. She felt relieved about this.

"Kojima-sama. It's good to see you again. Did you finished your mission already?"

Hiiro nodded and smiled as he patted Aoi's head gently. The golden eyed boy asked about the loud voice. She told him about the three kids Shinobu rescued, they are currently going through rehabilitation and training to boost their abilities.

"Oho, a training. Shall we pay them a visit?" He took a little glance to the girl, a small pink blush could be seen on her face. "Maybe I can meet that loud boyfriend of you."

"H-he's not my boyfriend" she squealed before walking to the where the training was being held.

The three boys were looking at the table with tea cups on it. Hiiro could tell about the concentration of the trio.
He studied the three.

The first boy was a blonde one, he could hear a silent cry coming from him.

The second one has a boar mask and the patient clothes are a mess with an unbuttoned shirt.

The last one he already met, the guy who carries a demon on his back. Tanjiro Kamado.

"Now!" Tanjiro moved swiftly but not enough. A girl with gentle pink eyes and coal black hair took a cup faster and drop it on Tanjiro's.

"Hey! What are you doing Monjiro?!" A pissed of boar cried as he tried to beat the guy while Zenitsu held him back.

"Well, well. Tsuyuri Kanao you are strong." Hiiro immediately recognized the girl, she met him more than once when he, Rengoku and Sanemi were new demon slayers. The were good friend with Kanae and for her even though she didn't show emotions, they are like her older brothers.

"Onii-chan..." she whispered. Kanao could not see much of the older Hiiro.

He was bigger, the body of a teen dissapeared, no he has an athletic body and more than that, his presence was different. "You're... back..."

"Yeah." He patted her head, all the others showed confusion. Even Aoi who knew Kanao since long time. "Five years is a long time, huh? I'm glad you remember me."

"Hey! Who are you?" The boar faced the pillar. A cocky grin drew itself on Hiiro's face.

"I'm the Night Hashira. Hiiro Kojima. Who are you boar?" His hand went instinctively to his sword. The three boys took a step back. "Who are you?"

"I-I'm Inosuke Hashibira. T-the King of the mountain!" He pointed to the pillar as Hiiro smile grew wider. "And don't forget the name!"

The pillars sharp eyes traveled from the boar to the blonde boy. He squealed and began to panic.

"Hey, it's rude not saying your name."

The boy bowed to the pillar as he repeated his name over and over again. The pillar began to laugh at the new two boys, amusing.

"It's ok, Zenitsu-San." Hiiro took a seat in front of the tea cup table and a grim smile appeared on his face. "Let's resume the training."

Shinobu sighed. Her stiff shoulders hurt like hell, but she has to train her body and mind. It was part of being a pillar.

The raven haired girl stood silent. She asked herself about the sudden peace in the estate, the loud boys weren't yelling anymore and their trainings haven't ended yet.

The master of the manor walked through the silent rooms and corridors of the butterfly estate. A sudden melancholy stroke the young woman, Shinobu realized how lonely and quiet the big estate can be. Not even Sumi, Kiyo and Naho were around.

"It's lonely..." she remembered Kanae again, would she feel like this sometimes?

When the insect pillar reached the training room she was dumbfounded by the serene and calm mood.

Everyone was surrounding the tea table. The girl instinctively went were the small crowd stood.

A sweaty boar masked boy stood face to face with a silent, patient and bored looking tenth pillar. When the newcomer was about to talk a terrific gaze fell upon her. A pair of shining golden eyes glared at her, she felt a cold shiver run through her body and like her legs were no more than jelly.

Such strong pressure coming from the boy with a single message. 'Do not say a word.'

"Now!" The boar swiftly took a cup of tea and prepared himself to launch the winning attack, but before he could do any of this, a barrage of tea stroke him.

"My win. Again." Hiiro smiled from ear to ear and then stood up. "Shinobu. Good to see you." He greeted politely.

The insect pillar greeted back and then with a warm smile asked about the reason why he was there.

"Shinobu-sama... You don't have to be so rude to Onii-chan.." Kanao whispered while hiding behind Tanjiro, a crimson blush in both of them.

"Onii-chan?" A stunned Shinobu asked, her eyes met with her little sister. She jumped a little and her grip on Tanjiros shirt became tighter. Like a scared rabbit fleeing from a fox. "He's no relative of you, Kanao."

"B-but, he's Kana—" before the young girl could continue Hiiro stopped her. He shook his head and then gave her a gentle smile. 'It's ok'. That was the message hidden in the smile.

"I'll take my leave." He walked past the insect pillar without looking back and the stopped. "Tanjiro, Zenitsu, Inosuke. Tomorrow at dawn your training will start. I'll talk Oyakata-sama about it."

As he was walking away, the kind hearted demon slayer caught up to him.

"Where are you going Kojima-San?" Tanjiro asked with a trembling smile on his face, he knew that the night pillar was upset. He will try his best to cheer him up.

"I'll pay a visit to Kanroji-san" he spat without looking back and like an autumn leaf, he dissapeared along the wind.

For Kocho Shinobu, this event should have no importance. But for some unknown reason her heart was racing and a growing rage inside her petite body, when she thought about the love pillar spending time with the tenth pillar, a raging smile appeared on her face.

"Kanao. I would like to have a nice chat with you. Now!" She ordered leaving the room more pissed than ever.