Before the duo could go to final selection, they first had to cut through a boulder each. They had been at this for six months, and Tanjiro was starting to give up. "You can't give up, Tanjiro," Y/N's voice mixed with two others, alerting the tired slayers in training; turning towards the sound of the voices, Tanjiro and Y/N saw a cute girl with a fox mask and a boy with another fox mask but with salmon pink hair flowing from the top of the boy's head. "Who are you both?" Y/N asked, suddenly remembering her most recent chat with Ren.
Flashback
"Y/N, there appears to be a multitude of souls around this area; you may meet them while training; the two brightest souls are a boy by the name of Sabito, who is most recognised by his salmon pink hair, and a girl by the name of Makomo, who is recognised by her beautiful mask and her hairpin. If you see them while you are trying to cut that rock, take all the help you can get, and be sure to tell them that I say hello."
Flashback end
"Are you two Sabito and Makomo?" Y/N questioned, bringing all the attention to her as the ghosts inhale, unsure how you know their names. "How do you know our names?" Sabito questioned as Y/N smiled, replying, "Ren Sylver says hello," "The chosen?" Sabito bowed, leaving Tanjiro confused, "She told me to take all the help I can get. Do you two know about my breathing form?" "I had heard only legend and what you said to the others when you woke up, but I sense that wasn't the full truth." Y/N smiled, "I should've known that you two would be able to sense that." Y/N laughed, "You are correct, of course, but I wasn't going to tell them or you everything. I have to keep one or two tricks up my sleeve," "How about I spar with Tanjiro and then Y/N to gauge both of your strengths. You don't need to worry about harming me." Sabito replied with a smirk. "We'll see who's smirking after this," Y/N said darkly, making everyone nearby nervous.
Time skip because of Tanjiro getting destroyed
"Y/N, it's your turn," Tanjiro puffed as he laid out of breath on the forest floor. "Excellent, time to go," Makomo started the match with a smile, saying, "begin," Sabito lunged forwards, startling Tanjiro with the speed of his attack, "Water breathing, first form," Sabito began, slashing toward the calm Y/N, "Killer breathing, first form: Bell Wraith," two bells sounded out as Y/N's image faded, becoming invisible. "Where is she?" Tanjiro questioned, speaking about what was on Sabito's mind. Y/N appeared behind Sabito, slashing towards his neck, stopping before she entered the flesh of the ghostly child, "I win," Y/N said, startling Sabito with the position he was in, "And I said we go until one of us lands a hit," Sabito replied knocking Y/N's sword away from her, "Fine, didn't need that anyway," Y/N huffed, "Killer breathing second form: Trapped," Sabito's eyes widened as beartraps appeared in the air around him, the metal gleaming under the moonlight, 'she can use her breathing style without her blade?' Sabito thought, "I won't move if I were you. Once you move, I win because it'll hit you." Y/N grinned, confidence seeping from her. Y/N turned away from Sabito to find her katana, a click coming from the traps as they latched onto Sabito, puncturing his skin and locking him in place. "Just phase out of it, Tanjiro is asleep, and I already know you both are ghosts," Y/N said to the trapped boy, who then phased in and out of existence, successfully escaping the traps, which then disappeared, "You did well, Y/N not many can beat me on their first try." Sabito stated, earning a gasp from Tanjiro, who had just awoken, "You beat him? You're so strong, Y/N!" Tanjiro exclaimed. "you're breathing style is very strong, Y/N. You only used two forms, which beat me in one move." "Thank you, Sabito. Now, where is my sword? Should I do that? No, it could kill everyone here." Sabito, Makomo and Tanjiro sweatdropped at this, with Y/N's sword stuck in the ground behind Y/N. "It's behind you, Y/N." "Oh, thank you, Tanjiro," a crack sounded as Y/N ripped the sword from the ground, destroying a large chunk of the nearby forest. Y/N smirked as she remembered her words before her fight. "Guess I was the one who had the last laugh, eh, Sabito?" Sabito sighed at Y/N's antics before laughing, "You are strong, Y/N; you can cut the boulder, but the next selection is in seven months, so you'll have to wait," Y/N smiled, striding towards the boulder, "That's fine, it's more time to train, I'm not stopping until this boulder is dust. Killer breathing, seventh form: Plagued air." The air around Y/N's sword turned green, with a smell of rotting flesh following it. Y/N slashed at the rock, and where the air touched it dissolved, cleaving a large path through the boulder. "Hmm, that's stronger than I expected," "YOU DISSOLVED IT. You didn't even need to cut it, and that's not your strongest form!" Tanjiro yelled, astounded at Y/N's powerful breathing technique, "Most of my forms are suited for fighting demons, not cutting rocks. It was one of the only forms that would work," Y/N replied, observing the still sizzling rock. "I vow to be as powerful as you, Y/N, one day." Tanjiro said thoughtfully, "I hope you will; I need someone by my side as strong as I am."
Time skip to when Tanjiro cut the rock
"Finally, Tanjiro, that took six months." Y/N exclaimed, bored as she had already annihilated the boulder, "That was still fast by most standards, Y/N." Urokodaki interrupted, "Now you both go to final selection and come back safe, ok?" "You don't have to worry, Urokodaki sensei; say bye to Sabito and Makomo for me." Tanjiro yelled back, surprising the old man, 'How does he know my student's names, I never said them, and they both died at their final selection' "Don't worry, old man, at least I have enough common sense to know they were dead, they helped Tanjiro a lot you know?" "I see," Urokodaki looked towards the sky, "Thank you, Sabito, Makomo. May they return safe because of your training and finally kill the demon that killed you both." "... What is this demon like?" Y/N asked, cold filling her eyes as her bloodlust slightly escaped, "It's a demon of hands, it has great strength, stronger than any other demon there." Urokodaki said to the powerful student, "Then it will fall to my own hands, slowly and painfully until the sun claims it's lack of a soul. I offer this revenge to you both Sabito, Makomo, I will make that demon fall to let you rest."
Final selection
"We're finally here, Tanjiro," "Yes we are, see you in seven days, Y/N, I wish you luck on finding that demon." Y/N started to dash into the gates before being stopped by identical twins, "You cannot enter until everyone has arrived," the twins both said in monotone, startling Y/N, "where the hell did you two come from?" 'They resemble to master of the demon slayers maybe they are his daughters?' 'Thanks Ren' Out loud Y/N asked, "are you two possibly the master demon slayers daughters?" "... How did you know that most people don't know about our father?" One of the twins replied, "I'm not most people, plus everyone is either here or at the top of the stairs now, so can we get started I have a demon to get revenge on," Y/N giggled releasing a large amount of bloodlust, 'This power,' 'I've never felt something like this before,' "This is stronger than last time, Y/N you really want that demon dead, don't you?" Tanjiro asked the giggling Y/N, "Not just dead, but I want it to feel the pain that it caused. ALL AT ONCE!" Y/N yelled the last part spooking the nearby demon slayers to-be. "Y-you can start now everyone can go inside! You have seven days to survive, then come back here." The twins said and Y/N was gone in a flash, giggling fading after her departure. "She was scary," the collected demon slayers gulped with Tanjiro confused about their fear...... "Where are you hand demon? Don't make me have to use my senses, I'll have to go to every demon signal until I find you, and that would be very boring." Y/N yelled into the woods, leaving hidden demons quaking, "Very well then, I'll start with the ones in the forest behind me then go find you," Y/N appeared in front of the first demon, "Killer breathing, Frenzy hook," A rumbling shook the mountain and a meat hook appeared in the centre clearing. Y/N's eyes turned blood-red, and she snarled grabbing up the demons and running to the hook, with the screams of five demons following her. "Your so annoying, DIE" Y/N shoved hook through the first demons head watching as he burned getting absorbed by the hook, the demons and slayers nearby screamed at the look on her face. "Tell me where the hand demon is," Y/N growled at the rest of the demons, "I-I don't know," the fourth demon replied, "then you have no use to me," the fourth demon screamed as she was absorbed by the hook, "The hand demon is about 4 kilometres to the south, please don't kill me..." "Thank you, you deserve a peaceful death, go now before I change my mind," "Not you two, I need more time to get to the hand demon," the hook glowed as the other two demons screams where cut off and absorbed. "To the south aye? There is only one demon that way, so I've found youuu." Y/N dashed off with the hook retreating into the ground with the skulls of those sacrificed left on the ground. "Her eyes turned red, is she a demon?" "No stupid, she was in the sun and the closest to Wisteria, she can't be a demon." ... "Boo," Y/N appeared behind the hand demon, slapping him into and through a tree. "Y/N?" Tanjiro asked weakly, "Tanjiro it's fine, rest he's mine anyway." "You aren't a demon, yet your power exceeds everything else, just what are you?" The hand demon asked, "I am revenge, and yours is well overdue, Killer breathing, second form: Trapped," "Huh killer breathing? What the hell is that?" Bear traps clicked around the hand demon, clamping down on him, making him scream, "Good, give me your screams. Let the Urokodaki students hear your pain and finally rest," "Killer breathing, sixth form: Entity's blade," A massive tendril of black and orange filled the air piercing the hand demon and dragging him into the air and dropping him into the ground, cracking it. "Why can't I move?" "Now you can't do anything, time to feel the pain you caused." Y/N cracked her knuckles and sheathed her sword. A pair of slayers run over but stop once they feel your anger, "If you want to be useful, help my friend, I have some business to attend to," Y/N grabbed one of demon's arms, slowly ripping it off. She continued to do this until the hand demon couldn't regenerate anymore because of so many injuries. "Y/N... You feel so much rage when you hear a demon has killed someone, because as someone who survived you feel guilt, even if you didn't know them." Tanjiro said glancing at the passed-out slayers next to him. "Your revenge has been served," Y/N quickly sliced the neck of the hand demon, ending his pain. "H-how long was I out for, Tanjiro how long has it been since I started?" Y/N franticly asked, looking at the passed-out demon slayers, "Four or five hours, Y/N you tortured a demon for four or five hours to avenge people." "I'm sorry you had to see that Tanjiro, I'll wake these two and leave you here, I don't want to bring any demons when you're injured. OI, wake up you two," Y/N yelled slapping both slayers awake, "Look after my friend, there won't be many demons that escape the scent of my blood." Y/N ran off, glancing back one more time to smile at Tanjiro. ... When Y/N thought she had gotten far enough away from Tanjiro, she took a breath and sliced her wrist, alerting every single demon on the mountain. Every demon stopped attacking anyone they found, they all turned towards Y/N. "Come at me you demon fucks," a yell came from every demon's throat as they charged Y/N, who just grinned, "Killer breathing, eighth form: Death's circle," Spinning in her spot, all of the demons who came into the yellowy-green mist either died by dissolving, or by a trap on their heads which shortly burst the demon's heads forever, "Father, the final selection has been cleared," the twins reported, "But there are still three days left?" The blind man responded, "most of the demons were killed by one slayer, Y/N L/N," "What? How did they do that?" "with one attack, killer breathing, eight form: Death's circle," "No wonder they all were killed, she no doubt spilt her blood to lure them all and then used a mythical breathing style form." "A mythical breathing style form?" "It cannot be taught for the user must be completely chosen and able to see the goddess, Entity's true form."
To be continued