Tanjiro and Y/n were in Sakonji's house. They were putting on their uniforms which had the Japanese mark for "Destroy" on the back. Tanjiro wore his Checker pattern haori over his brown uniform while Y/n used a white cape with the Japanese mark for "Wind" on it to cover his black uniform.

Sakonji: Are you both finished changing?

Tanjiro: Yes.

Y/n: Almost.

Y/n put on his bird mask and Tanjiro showed that his mark looked a little more spread on his forehead.

Y/n: All right, I'm ready.

Sakonji: Tanjiro and Y/n, now that you both have officially became Demon Slayer swordsmen, I would like to explain a few things.

Tanjiro: Right.

Y/n: What kind of things?

Sakonji: First, the Demon Slayer Corps uniforms you're wearing is made with a special kind of fiber. They're lightweight, water resistant and non flammable. A low-level demon's fangs and talents are incapable of penetrating that fabric.

Tanjiro: It's that strong.

Y/n: Yeah, but stronger demons are still able to penetrate it. Look, if you're just going over the basics, old man, I'd like to wait outside.

Sakonji: Very well then.

Y/n: Thank you.

Y/n went outside and sat in a tree, he then closed his eyes and saw a younger version of the pink tunic girl.

Young Kanao: Uh, hello. I am Kanao Tsuyuri.

Young Y/n: Well, it's nice to meet you. I'm Y/n L/n.

They shook hands and Y/n heard...

???: Y/n!

Y/n opened his eyes and saw Tanjiro with a wooden box strapped to his back.

Tanjiro: Come down here, Mr. Urokodaki's going to see us off!

Y/n: You got it.

Y/n jumped down.

Tanjiro: All right, we're off.

Sakonji: Before you go.

Sakonji fixed their clothes up and they went off for their mission.

Y/n: So, Tanjiro, is Nezuko in that box?

Tanjiro: Yeah. You doing okay in there, Nezuko?

Nezuko didn't answer.

Y/n: She's probably sleeping. Old man Urokodaki did theorize that she regains strength by sleeping.

Tanjiro: You're probably right.

Y/n: Well, I got some more of my memories back.

Tanjiro: Oh, really? What kind?

Y/n: It was something about that girl at Final Selection. Her name is Kanao Tsuyuri.

Tanjiro: How did you know her?

Y/n: She was a student of two of my former ladies.

Tanjiro: Oh, were you two close?

Y/n: Not really, all we did together was spare.

Tanjiro: So, how come I smelled the scent of Happiness coming from you?

Y/n: That was when I thought she wanted to be friends, but apparently she only talked to me because her master told her to.

Tanjiro: Well, I'm sure she's sorry and that she didn't mean to hurt you.

Y/n: Let's just focus on killing the ass hole demon we find.

They made to a bridge that led to a town.

Tanjiro: A town to the northwest, looks like we found it.

Y/n: All right, let's see what kind of information we can get out of the people.

They walked through the town and they walked by a beaten up looking man in a blue kimono and a brown haori, they then heard whispers from the towns people call the man Kazumi.

Random Man: It's happening every night, it's very creepy.

Women: Tragic, dreadful.

Women 2: As soon as night falls, another girl will be abducted.

Tanjiro ran after Kazumi.

Y/n: Tanjiro, where are you going?

Tanjiro: Mr. Kazumi.

Kazumi turned to Tanjiro.

Tanjiro: I want to hear what happened last night, from you.

Y/n: Me too, and we want the full story.

Tanjiro, Y/n and Kazumi went to the scene of the incident.

Kazumi: This is where Satoko vanished. But I'm sure neither of you believe me.

Y/n: You'd be surprised.

Tanjiro: What he means to say is, we do believe you! We're here to help.

Y/n: Believe it or not, we're private detectives sent here because of the missing girl reports.

Tanjiro: Uh, yeah. Now, let's see!

Tanjiro got on all fours and start sniffing.

Y/n: You got anything yet, partner?

Tanjiro: There's still a faint scent of the demon here, but it's uneven. Something's off.

Kazumi: Are you sure you two are private detectives?

Y/n: Want me to use some interrogation methods on you?

Kazumi: What?

Y/n got in Kazumi's face.

Y/n: I think you know a lot more than your letting on. You know, when you deceive people it always comes back to haunt you in a big way. Maybe I should show you.

Kazumi was terrified.

Kazumi: N-no! I swear, I'm te-telling you two everything I know!

Tanjiro: Y/n, stop. We're trying to find a girl, not scare people.

Y/n: You're lucky my partner was here to save your ass.

They started looking all over the town and even getting some looks from the people.

Y/n: Eyes on what you're doing.

They kept going until the sun started to go down.

Kazumi: I want you two to believe me. She really did just vanish.

Tanjiro: We know. That's why we came here, so we can stop this.

Nightfall struck as they kept walking.

Kazumi: Are you two really gonna to keep going?

Tanjiro: Yes.

Kazumi: Come on, it's getting late. I'm flattered that you two are so concerned about this, but shouldn't you two rest and pick it up again in the morning?

Y/n: You wanna sleep for the night, be our guest.

Tanjiro grouch down.

Tanjiro: They're only active at night. So, there's no time for us to rest. I got something.

Y/n: What is it?

Tanjiro: There's a new scent in the area. It's nearby, it won't be long.

Kazumi: Wait a second... don't tell me you two are really... are you two...

Tanjiro and Y/n felt something in the air and ran to the source.

Tanjiro: The scent got stronger! The demon's active!

Y/n: I can feel it's bloodlust.

Tanjiro jumped on a wall while Y/n went so fast that he broke the ground and they both stop at a point.

Tanjiro: This is it.

Y/n: Be ready. If you hesitate, you'll die.

Tanjiro drew his black sword while Y/n drew Eleatara.

Tanjiro: We gotta be careful. I also smell a human girl.

Tanjiro focused on the smell and and stabbed the ground which swamp water came out of. He saw a girl in there and pulled her out. A demon with red eyes, long purple hair and three horns came from the swamp water with a healing wound on its shoulder

Tanjiro: What did you do with the girls you kidnapped?

The demon responded by making an ear piercing sound by grinding it's teeth.

Y/n: Hey! Quit grinding your teeth and answer his damn question.

The demon continued to grind its teeth as it sunk back into the swamp and that's when Kazumi showed up.

Kazumi: Who was that?

Y/n: Doesn't matter. You take care of this girl and stay out of the way, while me and Tanjiro kill this son of a bitch.

Tanjiro gave the girl to Kazumi.

Y/n: Finding this thing won't be easy, Tanjiro.

Tanjiro: I wouldn't be surprised if it could appear out of thin air. But it doesn't matter. Because even if it's submerged, it can't erase its scent.

Tanjiro ran back.

Tanjiro Water Breathing, Fifth Form!

As he stepped his foot three swamp pools appeared and two demons that looked like the first one except for the number of horns came out of two of the pools.

Tanjiro: There are more!

Tanjiro jumped out of the way.

Tanjiro: (Thinking: Take it easy, you've got this! Eighth Form, Waterfall Basin!)

As Tanjiro was falling, he slashed his sword vertically making a waterfall like attack, hit the demons.

Flashback.

Sakonji: Tanjiro, Y/n, listen to me closely. There's only one demon that has the kind of blood that can turn a human, just one that's it, in the entire world.

Tanjiro: Just one? But Y/n said he got turned by a different demon.

Sakonji: It's probably a demon that this one demon trust. This demon, the first there ever was, he's been here for more than a thousand years. He's your target, the ones who attacked your family, Tanjiro. More importantly, I believe he's also the one who knows how to turn your sister back to a human. That demon's name is...

Y/n/Sakonji: Muzan Kibutsuji.

End Flashback.

The three demons got their arms cut off.

Tanjiro: I missed all the vulnerable spots! Because I switched forms midway through!

The demons sank back into the swamp.

Y/n: Three demons is not what I expected for our first mission.

Tanjiro: I thought demons don't usually work together.

Y/n: Its Blood Demon Art must let it clone itself or something.

Tanjiro: We have to take them all out and still protect these two. We gotta get anything about Muzan Kibutsuji.

Tanjiro jumped backwards.

Tanjiro: Total Concentration. Water Breathing, Second Form: Water Wheel!

Tanjiro slashed one of the demons with Water Wheel, but only got the demon's shoulder and it got into a safe distance from them.

Demon: Bastards! She'll go stale! Move out of the way, you little punks! The girl's 16 already, she's losing flavor by the second. If I don't eat her soon, there won't be any left at all!

Y/n: Did I hear that shit right?

Another demon came from the swamp.

Demon 2: Take a breath, other me. Calm down. No big deal. Nights like this happen, right? I've already feasted on plenty of this town's 16-year-old girls. And every one of them was meaty and delicious. I am satisfied with that.

Demon: Well, I'm not satisfied at all, other me! I want to devour all of them!

Kazumi: Monster. Bring Satoko back. The girl you took the other night!

The final demon appeared and made its presents known by grinding it's teeth and another one joined.

Demon 2: Satoko? Which one was that?

The demon showed he had a bunch of hairpins in his tunic.

Demon 2: If her hairpin is in this collection, then I'm afraid I've already eaten her. Sorry.

Kazumi broke down into tears when he saw the collection. The demons disappeared and one tried to attack Tanjiro, but he dodged and cut the demon's arm off.

Y/n: Tanjiro, focus. You keep missing its neck!

Tanjiro: He moves so fast.

A swamp demon tried to get Tanjiro from the wall, which Tanjiro avoided. Two then tried to strike Y/n.

Y/n: Total Concentration. Wind Breathing, Third Form: Clean Storm Wind Tree.

Y/n defended himself, slashing one of the demons neck and slashing the others arms off.

Y/n: Damn. I only cut ones arms off and I wasn't able to make a deep enough cut on the others neck.

Y/n got stabbed in the back by one of the demons and Y/n dropped his head down.

Demon 2: I got one.

Kazumi was in complete terror, but then laugher was heard and Y/n rose his head up.

Y/n: Holy shit, that hurt.

The demon tried to strike Y/n again, but Y/n caught it.

Y/n: Don't try that again, you fucker.

Demon: How the hell are you still alive?!

Y/n threw the demon. Meanwhile, Tanjiro was gonna get hit from behind by another demon, but Nezuko's foot popped out of the box and twisted the demon's neck in a really twisted way. Then the demon Y/n threw spoke.

Demon: Why in the world would a couple of demons be traveling with a mere human? And why is one a damn Demon Slayer?

Nezuko grew to her normal size and step out of the box.

Demon: It doesn't make any sense.

The demon sank back into the swamp along with the one Nezuko kicked who healed its neck. Nezuko looked at Kazumi and the girl and put her hands on their faces.

Tanjiro: Nezuko.

Tanjiro and Y/n remembered something Sakonji told them.

Sakonji: I don't know if this will give you two any comfort or not, but while Nezuko was asleep, I used the hypnotic suggestion on her.

Tanjiro: What for?

Y/n: It better be a good reason.

Sakonji: I convinced her that all humans are her family, I told her to protect them. The demons are your enemies! If a demon harms a human, never forgive them!
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Preview.

Tanjiro: You're kicks really saved the day, Nezuko! Thanks!

Nezuko: Hmm.

Tanjiro: And the box didn't even break after you kicked your way out of it! It's super-strong!

Nezuko: Mmm hmm.

Y/n: If you're this strong now, think of how strong you'll be once you get your Blood Demon Art. You'll be even greater than you are now, if that's possible.

Nezuko turned and blushed a little.

Tanjiro: But isn't it a little cramped in that box? It looks awfully uncomfortable.

Y/n: Well, discomfort is a small price to pay to make sure she doesn't burn in the Sun.

Tanjiro: Now, it's time for a Taisho-era secret! You know that three horned demon? I heard he's been constantly grinding his teeth like that ever since he was a human. Next time, Chapter 7, "Muzan Kibutsuji"!

To be continued.