Note: Apologies if it took a month to upload since I've been focusing on too much work (from home) lately. I'm working on Chapter 12 but there's no guarantee it will be uploaded early.

A long time ago...I was someone who had a different life...

Under the moonlight, a figure of a girl about fourteen or fifteen years old panted as her hand holding her sword couldn't stop shaking. There was blood everywhere, on her hands, on her kimono...and on her face. The smell of blood is strong but all of her attention is more focused on the lifeless body in front of her. It belonged to an unknown man who had its chest split open from a clean and swift strike.

"..."

The girl blankly stared, not even fazed at the permanent terrified expression on the man she had just slain. Not even the fact that she had cut deeply that his guts spilled out from fatal slash stirred anything that resembled regret and disgust. All she can see is she had killed a man who is now lying in his own pool of blood.

"Is this what you were afraid of, old man?"

She begun questioning herself, lifting her hand and revealed the blade reflected in the moonlight. She raised her hand, her eyes fixated on the sword stained by the blood of the unknown victim.

"Why is the world like this? Why are they so twisted...more than a demon like me?"

The girl, in despair, begun questioning herself and the reality she is forced to learn through bloodshed. Anything that can be called "innocence" instantly vanished in her heart, her eyes grew dull and unhinged as if shutting down her warm emotions so she would not lose her sanity.

"Why is everything so twisted...?"

Lowering her arm and loosening her shoulders, the girl whose whole figure is painted by the victims she is forced to slay, turned around to reveal she had slain more than one man. Scattered everywhere where corpses who had suffered the same fate as the unknown man.

"What's this aching feeling in my heart? Is this pain...because I didn't really want to kill them...?"

The girl couldn't understand her intense emotions, unable to comprehend the pain she had caused to herself. Her shaking and bloodied hand reached for her chest, wrinkling her blood stained kimono as she couldn't stop the tears flowing out of her eyes.

"Why did I kill them? I didn't even want to kill them...even if they did something bad...to other people..."

The deed is done yet the girl is wrecked by the guilt she also couldn't comprehend. Her thoughts had been thrown into chaos since she unintentionally murdered several people. Right before her are dead humans who suffered terrible deaths at her hands. Their limbs severed, throats slit, and even their heads where decapitated. It was a merciless massacre that she had caused...without knowing why.

Just why...

"...?!"

Shinobu gasped for air, immediately raising herself and frantically looking at her surroundings as if she had a nightmare.

"Just a bad dream, huh..."

She had dreamed of someone else she could faintly recognized but it was as if she was present during the terrible dream. Shinobu awakened inside a run-down and abandoned house deep within a mountain where she currently resides.

"It's hot. It must be morning already"

As a demon, she can't withstand the sun and she's particularly sensitive to its heat so she can recognize whether the sun had risen even when taking shade inside the house.

Ah. You're finally awake...

"Demon..."

You were practicing all night

"Practicing? Ah, that's right. I've been trying to train myself since I have more than enough swinging strength"

Shinobu picked up the sheathed blade she always placed at hand's reach when she's resting or asleep. Even if she's not anyone's target as of the moment, she's cautious since she cannot risk the possibility of a demon or demon slayer taking by her surprise.

The breath of water you learned by constantly watching that water Pillar friend of yours

"I suppose watching Tomioka-san practice his moves proved useful but I can't master the breath of water like he can"

Shinobu knew that while she could perform the breath of water from learning its moves from Giyuu, she is incapable of mastering it on a level like him.

That would take years but you're a demon so you have all the time to master it. That is if your demon hunter friends doesn't cut off your head...

"I won't let myself go down at anyone's hands but I don't wish to kill my former allies"

Hmph. Good luck with that...

While Shinobu resolved to continue living as a demon, she still clung to her humanity as she stated she would never cut down other demon slayers.

Well, you need the resolve to live since we have a doctor to chop up until he pleads for mercy

"..."

Shinobu?

It's because of a wretched demon doctor you and I are physically fused. You lost your body while I became a demon...

Shinobu looked at her hands with sharp claws capable of tearing through human flesh. While there is no mirror lying around to view her own reflection, she knows she grew fangs and distinctive demon eyes.

Look on the bright side, you didn't lose your humanity and you could still use breaths since you were a Pillar

"I would never let go of my humanity because of this hatred"

What a cruel joke for the two of us. You hate demons so you became one and I hate humans...so I became stuck with one

Shinobu is visibly furious and seeking revenge for her second life as a demon but even the demon Akane is furious since she had lost her body by being merged with a demon slayer who bear seething anger for all demons.

Feel free to choose what you want. I won't care unless it concerns both of our lives

If Akane had a body she'd shrug off her shoulders as she tell Shinobu she has little care for her decisions that isn't life of death for them. It's obvious she'd care since if Shinobu dies, she dies as well. While her life as a demon prior to her current situation isn't the most exciting, she's not suicidal and wants to live like other people.

"I noticed you're changing, demon. You're becoming behaved and less annoying"

Is that so? I didn't really notice myself since I always worry that you'd get both of us killed

"I can't believe I'm saying this to a demon like you but I'm getting accustomed to you"

I could say the same thing to you

The two admitted that they're starting to understand each other so they started to tolerate each other with the days they communicate and work together as two consciousness sharing the same body. Although the body belongs to Shinobu and some of Akane's parts were just "transplanted" to Shinobu who was minutes from dying.

So where are we heading tonight? Your forms are still incomplete but still have to take on demons

"You don't seem to care much about your fellow demons, do you?"

I'm a demon who was taught to rely on my own. I'm not obliged to care about other demons like how humans don't really care for people they don't know

"That's true..."

Shinobu sighs as she reluctantly agreed how Akane cares very little to other demons she doesn't even know is similar to humans not caring about the lives of most people around them.

Somewhere

Much like some other days, Tanjiro goes on his solo mission but he had gotten used to it for a while now. He's been used to working together with Zenitsu, Inosuke, and Kanao but he learned to quickly adapt in a solo fight and besides he always has Nezuko who will aid him in the fight if necessary.

"I wonder what happened with Kanao on that mission. She knew she was saved by someone but couldn't remember who it was. If only I didn't get knocked out easily"

Tanjiro lamented how he was rendered unconscious after the back of his head was slammed against a tree and knocked him out. The demon they were fighting was finished by someone who saved Kanao but the latter has no memory who it was which Tanjiro found it strange.

"There's also Giyuu-san who met a masked swordswoman when he was with Rengoku-san and the rumored sword wielding demon. Mysteries are happening lately"

Even among those mysteries, there's one he has yet to solve or make progress after a couple of weeks.

"The demon with Shinobu-san's scent. Ever since then - I wish I could encounter that demon again since it quickly left"

The biggest mystery he wanted to solve was the fact that he fought a demon who had Shinobu's scent. He found this obviously strange and unbelievable since Shinobu was presumedly dead even when her body was never recovered"

"That demon couldn't possibly be Shinobu-san even if it had her scent"

Tanjiro shakes of the thought that Shinobu had indeed turned into a demon but he's beginning to fear of the possibility because of the Love Pillar'd encounter with the unknown demon.

"Kanroji-san said she saw a demon who looked exactly like Shinobu-san and even sounded like her but the demon denied it. At least that's what she said what happened"

Since Tanjiro isn't really present when Mitsuri encountered the unknown demon, he can't say for certain whether the demon is indeed Shinobu or not. If he was there, he would be able to recognize the scent if it was true.

"Wait, the demon Mitsuri-san encountered and the one with Shinobu-san's scent. Mitsuri-san said it used some sort of poison to affect her senses when it blurred her vision. The demon I faced...had a similar Blood demon art..."

Tanjiro then realized that the two demons used some sort of poison that can affect their target's senses which made it look like that the two demons could possibly just the same demon.

"I'm overthinking this. Maybe they just have similar Blood demon art. Wait, can demons even have similar powers?"

Tanjiro isn't sure about it since he hasn't fought demons who had similar Blood demon arts but the possibility is still open as there are more demons with Blood demon arts he hasn't faced. He doesn't want to assume without more evidence so Tanjiro set aside the hypothesis of the two demons just being the same demon.

"Hmm?"

He caught a scent of fresh blood and malevolent scent present with most demons just before he entered and intersection in an empty street. He quickly positioned himself, his hand on his sheath and hilt, preparing to strike as soon as the demon presents itself.

(This scent. It looks like this demon had just eaten somebody!)

The scent of human blood and demon's blood thirst brought anger to Tanjiro who doesn't tolerate anyone who would kill someone especially if it's a demon who had just fed on a human.

"...?!"

Just as he drew his blade by an inch, he widened his eyes in disbelief when the demon he detected is someone wearing a demon slayer uniform and holding a nichirin sword.

"It can't be..."

There's no mistaken that the one in front of him is a demon who had just eaten a human. The demon's blood running down from its mouth down wasn't his but from the human victim. He hesitated to draw his blade since the demon he must decapitate was a demon slayer like him but somehow became a demon.

"Rrrhh...grr..."

The demon struggling to walk properly, immediately noticed Tanjiro and stiffly turned to face the conflicted demon slayer.

"Rrraaaaah...!"

No longer possessing any form of sanity or consciousness, the demon immediately turned aggressive and rushed to Tanjiro like a starving predator spotting a prey.

"...?!"

The demon who used to be a demon a slayer lunged but Tanjiro easily dodged his mindless enemy.

"Aaarrrgh!"

The demon screamed when one of its arms is instantly severed in a blink of an eye. A mindless demon like that can be killed by Tanjiro in one attack but he is visibly reluctant to kill it as he never fought a demon who was once a demon slayer.

"There's no way to save him now. He had lost his mind and only has the instinct to eat humans..."

While the demon wait for its arm to regenerate, Tanjiro realized that the demon can't be reasoned with as it is now rendered with only the basic instinct to feed.

"Even if you were a demon slayer, you had become a demon and had eaten a human so I must decapitate you"

Tanjiro knew he must slay the former demon slayer as not only it had lost its sanity but had already killed a human. If he let this demon escape, it will kill more and that he cannot afford to happen. He has his duty as a demon slayer so he must this before it kills more innocent people.

"Farewell..."

The demon charged bearing its fangs and Tanjiro charged as well with his blade drawn. With certainty, Tanjiro swung his blade until it made contact with the demon's neck and cleanly slice from the start to the end. One swift slash to the neck is all it took to separate the head from the body, ending the demon slayer who had fallen.

"May your soul rest in peace"

As the corpse fades away like every demon who had their heads decapitated, Tanjiro at least prayed for the demon with visible sadness in his eyes. Tanjiro is someone who is full of compassion and empathy so slaying someone who was a demon slayer was something he did with a heavy heart.

"...?!"

Hearing a bell and a cat's meow, Tanjiro spots a calico cat with a piece of scribbled paper on its head.

"You're...Tamayo-san's cat..."

Tanjiro recognized the trained animal not only from its appearance but from its scent which isn't exclusive from detecting humans or demons nearby

"He's called Chachamaru"

Of course he also recognized the irritated voice of a boy even before revealing himself to Tanjiro.

"Yushiro-san!"

"You hesitated for a moment but you quickly finished off that demon"

After Yushiro revealed himself to Tanjiro, he commented on the brief fight earlier with the mindless demon. Like usual, he sounded hostile to Tanjiro even if they're not enemies. Then again, it's Yushiro's usual attitude towards anyone with the exception of Tamayo whom he greatly admires.

"You were watching me?"

"I wasn't watching you but the demon. You just happened to be there"

"Why?"

"Tamayo-sama and I are investigating demons like that. Demons who were once demon slayers"

"What?!"

"Hmph. If you want to know more, follow me. I don't like talking out in the open"

Yushiro quickly turns around and starts walking away while Tanjiro follows him shortly after. He's curious to what he meant when he said Tamayo was investigating demons like the one he killed earlier like there were more of it. Neither of them said anything after walking for more than ten minutes, making several turns until reaching the boundary of the town.

"To think you'd be here of all places" Yushiro scoffed

"I was just on a mission and I didn't know you were here so it's just a coincidence but I'm glad to see again Yushiro-san"

"Hmph! Whatever..."

When they first met, Tanjiro knew how Yushiro has little to no tolerance towards others but he doesn't view the demon as a bad person. Tanjiro is kind and polite to people who hasn't harmed anyone, even towards demons.

"Tamayo-sama, I have returned" As usual, Yushiro speaks in a docile and calm manner towards Tamayo

Mixing an unknown liquid in a tube and studying what seems to be a piece of flesh, Tamayo is briefly surprised at Yushiro bringing along Tanjiro but he greeted the young demon slayer with her gene smile.

"It's been a while, Kamado Tanjiro. How is Nezuko doing?"

"She's doing fine as usual"

Due to Tamayo's genuine gentle and warm demeanor, Tanjiro feels at ease and comfortable towards the fugitive demon doctor. He doesn't mind if Tamayo is a demon since he's the first one he met who has no blood thirst or violent intentions.

"Nezuko, we're at Tamayo-san's house. You can come out now"

Tanjiro gently took off and put down the strapped box carrying Nezuko then gently tapped the top as she whispered to it. The door creaked open, a shrunken Nezuko shyly crawling out and looking at the interior of the house.

"Good evening, Nezuko"

"Mmm-hmm"

Tamayo waved her hand and greeted the still shrunken demon who raised her hand from her oversized kimono to wave back at her. Of course she turned to wave towards Yushiro who just looked away frowning.

"Yushiro, where did you meet Tanjiro? I never expected you'd return with him"

"Tamayo-sama, he encountered one of those demons again and quickly killed it. I was watching the demon's movements but he was there by chance"

"So you were able to eliminate it. Was it hard for you, Tanjiro?" Sympathetic, Tamyayo softly asked

"It was. The demon was one of my allies but it had killed someone so I had no choice but to take it down. I couldn't stop it from killing anyone"

Tanjiro lowered his head, saddened how he couldn't prevent the demon from eating humans. The demon had already lost his sense of self so Tanjiro decapitated it even when he initially hesitated. He knew a demon like that is beyond saving and he had to kill it to prevent it from killing more humans.

"That demon was perhaps like the others. Victims reanimated as demons"

"Victims?" Tanjiro raised his head

"Yushiro and I have been investigating about how dead bodies return as demons"

"You mean a dead person came back as a demon? Is it even possible?"

"It's not impossible for a demon's Blood demon art so I'm tracking down who could have been using dead bodies as demon puppets"

"Why...why would they reanimate bodies as demons?"

Tanjiro clenched his fist in anger while Nezuko holds his hand seeing her older brother about to pop a vein from anger. Tanjiro looked down, seeing Nezuko worried at his anger so he returned to his kind expression and pets her head much to Nezuko's delight. Even if Nezuko's mind had regressed to that of a child, she instinctively wanted to comfort Tanjiro whatever emotion he is unable to restrain, especially anger.

"It's unforgivable. To use bodies like puppets when they should just be laid to rest..."

A dead person should be buried to lay them to rest and return where they came so reanimating dead bodies as mindless demons is defiling the deceased and an act for twisted sadism. Such thing is unforgivable for Tanjiro who slays demon while remaining kind.

"This has been going for a long time and the alarming fact demon slayer bodies are being used is why we're trying to identify the culprit"

"I want to help, Tamayo-san. I will find him and defeat him so no more bodies will be used as puppets"

"Thank you, Tanjiro. If it's you, I know it's possible"

Tanjiro didn't hesitate to offer his help to Tamayo in tracking down the demon to put an end to the reanimated corpses mindlessly killing people all over Japan. He won't forgive the act of cruelty so Tanjiro wanted to hunt him down if he could find him before more demon slayers are reanimated.

"By the way, Tamayo-san...the demon slayers that were reanimated..."

"The demon is probably experimenting whether demons who were once demon slayers is stronger than average demons due to how they train to pass their physical limit"

"Are they all mindless or could some of them keep their sanity?"

"I don't know if it was a reanimated corpse but there was one but it was Yushiro who encountered it..."

Tamayo looked towards Yushiro so Tanjiro looked towards him as well. Yushiro hesitated to speak for a moment but Tamayo's nodding urged him to report it to Tanjiro as well.

"I saw one. A demon with a uniform like yours but she had a haori"

"Really?"

"She was capable of using breaths like the demon she was fighting. Of course she killed it by decapitating its head so she was using a nichirin sword like you. I didn't stick around to find out who she is since I might lose my head too"

"A breath using demon who kills other demons. Could it be..."

Rengoku Kyoujuro mentioned how he's tracking down a rumored demon who can use breaths but hunts down other demons. Tanjiro believed there could be a connection or the demon could be the rumored demon itself.

"Is there something wrong, Tanjiro?"

"The truth is, a Pillar I know died a few months ago but her body was never found. A few weeks ago, I met a demon who had her faint scent then lately another Pillar saw a demon who looked like the Pillar who died"

"I see. So you're speculating whether this deceased Pillar was a reanimated corpse"

Tamayo placed her hand on chin, thinking about the possibility of the deceased Pillar reanimated as a demon but with her sanity intact unlike the others.

"The Pillar who died was the Insect Pillar who chased after a demon even when she was heavily wounded. My friend Kanao didn't find her body but find her sword in a pool of blood"

"You said the body was never found so it's possible she was taken to be reanimated like the others"

"The demon I fought had no intention of killing us just judging from the scent and it had Shinobu-san's scent but I'm not sure whether it was her or someone pretending to be her"

"It's possible your Pillar friend was another victim as well but there's also a possibility of a demon impersonating other people. If my Blood demon art can conceal anything except existence, there could be a demon who can mimic appearance and scent out there" Yushiro shrugged his shoulders

"You're right...but nothing is confirmed yet. I have to meet this demon again..."

While what Yushiro said could be a possibility as well, Tanjiro has yet to jump to conclusions yet until she confronts the unknown demon for a second time.

"If this Pillar friend did indeed turn into a demon, there's a chance she will not recognize you or remember her human life at all. Will you take her down as well?"

Tamayo wanted to prepare Tanjiro for the worst case scenario if he indeed confirm his suspicion so she already informed him how the Pillar he's seeking may not recognize him and possibly attack him on sight.

"I have my duty as a demon slayer. If Shinobu-san is like the demon I fought earlier...then I will have no choice but to defeat her"

Tanjiro closed his eyes for a moment and furrowed his eyebrows upon reopening them, responding how he will have to slay the demon. He will have no choice but to take down if the enemy before him cannot be reasoned with. That is what he chooses to do as a demon slayer seeking a way to undo his sister's demon transformation.

Chapter 12:

Tracking down a rumored breath using demon, Giyuu finds himself not up against demons but reanimated corpses. As if by fate, the mysterious swordswoman appeared before him. Meanwhile, Tanjiro discusses what he learned to his group.