Katy knows what the supernatural is. She's seen kitsune, and dragon-horses, and Morris, and an actual dragon. On top of that, she's seen creepy soul-stealing tentacle bats and their scarier tentacle bat master. She's driven through a bamboo forest that wanted to eat her, shot said tentacle bats with a bow, and convinced her formerly-assassin best friend who controls some of the most powerful ancient weapons to teach her how to fight and defend herself.
Which is what she's repeating to herself as she glances over shoulder. It's late, she's walking back to her home, and there's a horrible itch on the back of her neck. Something is following her.
Now that she knows about the supernatural, has interacted with it first-hand, she knows that it might not be a someone.
She takes a deep breath and decides to take a shortcut through an alleyway, one she's used before. As soon as she turns the corner, she breaks into a run. The itch fades, and she slows down with a sigh of relief. Then Katy sees the thing waiting for her at the end of the alley. It's blocking her off from the end of the street.
Katy knows it's not human. The t-shirt and jeans it wears are ripped and stained with what has to be dried blood. It has twisted, spiky horns and long, dirty hair, and nails that look like claws. Its legs are twisted and digitigrade and spikes protrude from its arms. And its eyes… they're black, sclera and iris, with white slitted pupils.
If she hadn't done her forms so often that they were muscle memory and instinctual by now, Katy would have been knocked over in an instant. Instead, she grabs the arm of the monster as it reaches for her and throws it over her shoulder. It flips out of the throw, landing on its feet and snarling.
"What the hell, man!" Katy yells. "What are you? What do you want?"
The thing hisses. "I've been laying low...there's a slayer around, but I haven't eaten in weeks! I'm hungry…I'M HUNGRY!"
Oh shit, this thing wants to eat her. The thought barely registers before it's jumping at her again, lightning fast, and she's not quick enough to avoid the hand that grabs her arm, claws digging into her flesh. Katy shouts and throws a punch at its throat, feeling a rush of relief when it connects. The monster chokes and lets go, and Katy stumbles back. What the hell? It's so fast!
Then she feels a hand on her shoulder and a polite voice says, "Are you alright, miss?"
Katy blinks. It's a kid, not more than fifteen, and he's carrying a katana in one hand. He's wearing a black shirt, tucked into black pants secured with a white belt. The pants are tucked into calf-high combat boots, and a loose loop on his belt has his sword sheath attached. He's also wearing a loose green and black coat and one of those large hiking backpacks.
"Kid, what the hell is going on? What is that thing?!" Katy looks back and forth between the kid and the monster, who is frozen in fear.
"It's a man-eating demon. I need to deal with it, miss." The boy has a determined look on his face as he quickly shrugs off his backpack. "Will you watch this for me? It's very important to me and it will protect you in case something happens. I'll come back when I've killed the demon."
With that, the demon seems to snap out of its frozen state. It screeches and runs, disappearing impossibly quickly. Katy is left with a handful of backpack as the boy rushes after it, somehow matching its pace.
"What the hell."
Katy sets the bag down. The cuts on her arm aren't that deep, thankfully. She's trying to come to terms with what she just experienced. Man-eating demons? Of course there were plenty of stories about the scary things that went bump in the night, but she had no clue where this fit in. That thing was so fast, but the kid had been just as fast as it.
While Katy is in the middle of her crisis, she hears shuffling from the backpack. Well, curiosity killed the cat, but satisfaction brought it back--Katy unclips the top. A small girl climbs out and proceeds to grow in height, and now Katy is pretty sure that something had been in her drink. The girl has pink eyes, long dark hair with orange tips pulled into a braid, and is wearing a pink blouse and knee-length skirt along with knee-high socks and sandals. She also has a wooden muzzle in her mouth.
"Who are you?" Katy asks. "Why were you in the backpack?"
The girl just hums, patting her arm. Now that Katy thinks about it, she can see that the girl has little cognition behind her eyes. And that muzzle. Katy doesn't know why she expected a response, actually.
They stand there for several minutes, the adrenaline high bleeding out of Katy's system. She's still on high alert, with the girl holding her hand now, but nothing seems to be happening. Of course, it's right when she lets her guard down when the demon returns.
Katy's warning is when the girl's grip tightens then abruptly lets go. A glance over shows that she's in a fighting stance. Katy's eyes catch on her nails, sharp and pointed. Then the demon steps forward. It's missing an arm, but there's not a lot of blood leaking from the cut. The cut is so clean Katy can see the white, circular bone in the center of the stump.
She shudders, quickly getting into her own stance. The demon must have lost the kid on its way back. It snarls, saliva dripping from its mouth, and Katy can see that there's no more intelligence behind its eyes.
Then it snarls and lunges at a blinding speed. The girl meets it halfway. Katy can only gape at the vicious punch that folds the demon in half like paper. Blood spurts from its mouth, and the girl steps back, letting it drop to the ground. The demon is shaking viciously on its knees and it doesn't look to be moving soon.
The boy from earlier sprints out of the darkness. He breathes deep and swiftly sweeps the demon's head off its shoulders. Katy stands still in shock, watching the monster's head roll on the ground. The boy folds his hands in prayer for a moment over the demon's body, eyes closed as he whispers, "To all the gods, please save this man from becoming a demon in his next life."
Katy just watches awkwardly for a moment. The demon dissolves swiftly into nothing. Sheathing his sword, the boy finally looks over to her. "Are you hurt, miss? I can smell blood."
"Oh, uh, it's nothing really, just a couple of scratches! I'm fine."
"Do you need any help at all?" After getting an affirmation, he huffs softly. "All right. Nezuko!"
The girl trots over to him. He smiles at her, then bows to Katy. "Thank you for taking care of her!"
"If anything, she took care of me," Katy huffs. "Anyway--who are you? What was that thing?"
"Oh, ah!" He bows again. "So sorry! I should have explained earlier! My name is Kamado Tanjiro--or Tanjiro Kamado is the western way of saying it, and this is my sister, Nezuko. As I said before, that was a man-eating demon. They are made by humans being exposed to demon blood. But they have to be high-ranking demons. Once a demon consumes a human, they lose any humanity they might have had." His eyes are sad. "They are dangerous and have to be killed. That's my job, as a Kanoe rank in the Demon Slayer Corps."
"Oh. Uh." Katy can't quite process all of that. "That's good, that people are taking care of the demons? I guess I should be going, though."
"I can walk you home if you like?" Tanjiro offers.
"No, I'm sure I'll be fine! It was cool meeting you, Tanjiro, and your sister. Maybe I'll see you again, bye now!" Katy waves, turns and leaves. She ponders the whole interaction on the way home. When she finally flops into bed, she realizes that she never told Tanjiro her name. Or figured out what was up with Nezuko. Oh well, she sighs, and closes her eyes. At least she'll have a wild story to tell the next time she meets up with the others.