Jörmungandr

Kyojuro stood directly across from me, we had relocated to a training ground at the Butterfly Mansion. The Fire Hashira put a hand on his sword preparing to draw it. My arms remained crossed over my chest. 

"Here I come Uchiha-san! Breath of Flames First Form! Unknowing Fire!" 

Kyojuro rushed at me at speeds that would put Olympic sprinters to shame. His nichirin blade glinting in the afternoon sun headed straight for my neck. My Sharingan spun to life and I easily dodged his horizontal slash. 

"Lesson one, shouting the name of your technique is wholly unnecessary." 

Not bothering to draw my sword I struck out with a fraction of my strength so I didn't hurt Kyojuro. An open palm strike pushed him back, my other hand quickly stole his nichirin blade's saya (scabbard). 

Holding the saya at my side I swatted the flat of his blade as he swung at me again. Kyojuro grit his teeth and smiled.

"Third Form! Blazing Universe!" 

Kyojuro slashed at me again, this time attempting to split me in half from the top down. I sighed and parried his downward slash. 

"Do you not listen?" With a flicker of movement I jammed the scabbard in my hand into the point between his arm and his side.

Kyojuro let out a low hiss of pain as his arm fell limply to his side. I had targeted his pressure point and temporarily disabled the use of his dominant arm. Still the young man refused to quit. 

"Second Form! Rising Sco-" 

Before he could finish shouting his move I bonked him on the head with the scabbard making him drop the sword and clutch the lump on his head. 

"Ouch! What was that for!" 

"I told you… stop shouting the names of your moves. It gives away too much to the enemy and wastes precious time. 

Kyojuro pouted but quickly recovered. I handed him back his scabbard so that he could put away his nichirin blade. He bowed slightly, and gave me a large smile. 

"I see, you have shown me where I need to improve. Thank you Uchiha-san." 

"Hn, also be mindful of your horizontal slashes, you almost over extend yourself every time and leave yourself open to a counter attack. Humans may not be able to land a blow but a relatively powerful demon could exploit that weakness." 

Kyojuro nodded again before turning over to Shinobu who had been watching silently from the porch of the modestly sized house. Next to her was another young girl with a similar butterfly pin in her hair. 

"Kocho-san, I believe you wanted to test Uchiha-sans skills yourself?" 

"Ara ara, you're putting me on the spot Kyojuro-kun." 

Shinobu smiled softly at the flame haired kid, however she still stepped forward with a hand on her nichirin blade. 

"Well… don't mind me then." She dashed forward, faster than Kyojuro. 

I hummed in surprise at the Insect Hashira's speed. She was on me in the blink of an eye. Her blade flashed out of her scabbard as she swung at me fast. 

I leaned back slightly causing her to miss. Shinobu still had a calm smile on her face. Her blade was unique, in the sense that only the very tip was actually a blade. 

The rest of the sword was thin and narrow, a greenish substance dripped from the tip of her blade. I narrowed my eyes at the sight. 

"Poison." 

"Correct… I'm not as strong as the others so I can't behead the demons I face. My blade is uniquely made so that I can administer a poison deadly to demons with just a small scratch." 

"I see." I hummed in reply. 

"Prepare yourself Uchiha-san." 

She dashed forward again, her blade blurring as she quickly struck at me with blinding speed. My Sharingan still caught all her moves letting me dodge them but I could see why she was a Hashira despite 'not being strong' as she put it. 

Her speed alone was enough to trouble me had I not been who I was. That being, a hilariously overpowered being that enjoyed going on zany adventures and avoiding my responsibilities. 

"You're telegraphing your attacks like Kyojuro." I coached her as she swung at my head again. 

"Ara… it seems like I can't beat you fairly Uchiha-san." Shinobu said with a soft smile as she continued to try and cut me. 

"Hn." 

Her attacks became more ferocious, I dodged and weaved through her strikes and stabs, eventually I grew bored and ended the fight with Kakashi's signature move. 

Shinobu's eyes widened when I blurred away from her vision only to appear behind her. Crouching low I brought my hands up to a tiger sign. 

"Konohagakure Hiden Taijutsu Ōgi: Sennen Goroshi."

Kyojuro's jaw hit the ground, Shinobu blushed furiously as I proceeded to introduce my fingers to her ass. Shinobu quickly leapt away while clutching her rear. 

"Y-you! How could you do such a thing to a woman?!" 

I smoothly and nonchalantly got up and pretended to dust my hands. Giving her a small grin I crossed my arms. 

"Lesson one in becoming a better fighter; expect the unexpected." 

"Oh… I see! One must surprise the enemy with a surprise move in order to open up the enemy's defenses!" Kyojuro exclaimed with a smile of understanding. 

"You… now no one will marry me! I'm a tarnished woman." Shinobu pouted. 

Still smiling at her, I put a hand on Ryujin Jakka.

"Fine… let me indulge you in a real spar." 

Shinobu instantly became serious and took her fighting stance again. Kyojuro was still making exclamations about how to surprise his opponents. 

I slowly drew Ryujin Jakka, making the temperature gradually rise around me. Shinobu visibly gulped and Kyojuro stopped raving about surprise attacks. Both Hashira were captivated by the small embers and sparks coming off of my blade. 

"To avoid injuring you I'll only use pure kenjutsu and I won't use my blades latent ability." 

Shinobu deftly nodded, Kyojuro was now taking notes with a notepad he had gotten from somewhere. Seeing both of them paying attention I spoke again.

"We're going to start off with 1% of my true speed." 

With that I disappeared in a blur of movement, my blade flashing through the air as I reappeared in front of Shinobu. She jumped back in a startle and instinctively brought up her sword to block. Steel struck steel with a loud clang, Shinobu slid back a few feet, her arms dropping to her sides. 

"I-what was that? I could barely keep track of your movements." Shinobu asked, her hands shaking as she readied her blade again. 

"That was just me dashing towards you and swinging my sword at a fraction of my power. Now, good instincts, jumping back and blocking. Do it again." 

I blurred away again and struck out with an overhead slash. Shinobu once again dodged my attack with pure survival instinct alone. The ground where she once stood shattered from the impact of my blade. 

"Come at me with the intent to kill or you'll actually die." 

Shinobu became serious, a glint appearing in her eyes as she readied herself. In a blur of movement she rushed at me faster than she had done before. Her specially made sword whizzing in the air as she slashed and stabbed at me with deadly accuracy. 

However it was all for naught as with the Sharingan I perceived all her attacks before she even made them. Dodging left and right and countered with my own attacks that Shinobu barely managed to dodge or block since I was holding back quite a bit. 

"It seems I have lost…" Shinobu let out a tired huff, "you are simply just too powerful Akimitsu-kun." 

She sheathed her Nichirin Blade and offered me a small bow. I followed suit after I put Ryujin Jakka back in its scabbard letting the temperature return to normal. 

"Comparing yourself to me would be setting yourself up to failure. You are one of the Hashira for a reason, Kocho-san. Any demon would fall before you easily should you reach the pinnacle of your abilities." 

"Any tips for us Uchiha-san?" Kyojuro asked. 

"Hn, I believe I can train you both to become even stronger. You'll be stronger than yo- our peers in no time." 

"Then we shall be in your care Akimitsu-kun." Shinobu said with her signature smile. 

"Hn." 

[Scene Break]

I began to train Shinobu and Kyojuro earnestly in my free time. It has been a month now since they began training with me. They have both made great strides in their training. 

Kyojuro learned the breathing style I had seen Tanjiro's ancestors performed. I later learned that this was the first and original breathing style created by Yoriichi Tsugikuni.

How I had come by this information was from cross referencing various texts and reports that were made available by Kaguya. 

Kyojuro had a difficult time at first, the Breath of the Sun was a complex series of moves that pushed the human physique to its absolute limit. Training with me, even for just a month had strengthened Kyojuro and Shinobu's bodies to perfection though, resulting in Kyojuro being able to learn 'Sun Breathing' without too many issues. 

Others shad come to watch, Mitsuri Kanroji, the busty Hashira joined in on the training sessions after Kyojuro bragged about how strong he had gotten just from the physical aspect. 

Mitsuri was already strong, surprising given her body type. She had taken to calling me 'Akimitsu-sensei' once I began training her to use her inhuman strength effectively. 

The three of them also became my first 'shinobi' students in this world after I granted them the ability to wield chakra. 

I taught them jutsus after testing their chakra natures. Unsurprisingly Kyojuro had fire, while Shinobu had earth. Mitsuri was the only one that surprised me after she was revealed to have dual affinities with wind and water natures. 

I had a feeling I could push her to develop ice release. Unfortunately I didn't know too many ice jutsu so I only taught her the jutsus pertaining to her natures. 

Kyojuro was excited to finally be able to use real fire with his attacks. Claiming that he was one step closer to becoming stronger than me. I encouraged this since I had grown to care for the three of them and didn't want them to die. 

Sanemi watched the training sessions with a look of contempt. He didn't think that I could actually teach him anything. That was the case until Mitsuri blasted him away with a wind jutsu and he begged me to teach him. 

I gave him an answer in the form of; 'Beat me in a duel and I'll teach you everything I taught them.'

It was an impossible task but it gave him something to focus on rather than stalking me or constantly challenging me to duels. He trained himself to exhaustion nearly every days since then. 

The other Hashira were too busy but my three students imparted bits of my teaching to them, this resulted in all the Hashira becoming stronger as they all started training daily too. 

I had been surprised to learn that they didn't train as much as they used to after becoming Hashira. It was no wonder that they hadn't managed to kill any 'moon' demons. 

[Scene Break]

"Akimitsu-sama!" 

I turned towards the sound, a Kakushi was standing at the porch to my home panting. I raised an eyebrow when I felt the distress radiating off of him in waves. 

"What is it?" 

I had Kakushi assigned to me to help clean up my battlegrounds and transport any injured slayers and civilians to the butterfly mansion. 

"There's been reports of a lower moon attacking slayers. Tomioka-sama and Kocho-sama have gone to assist the slayers at Mount Natagumo." 

"I see… if two of my fellow Hashira have already been deployed then why have you brought this to my attention?" 

"You told me to inform you if the Kamado kid was involved with anything, he was one of the slayers first dispatched to the mountain." 

"Hn… very well, I shall go assist then. Thank you Kakushi-san." 

The Kakushi nodded before dashing off, I stood up from where I was seated and picked up Ryujin Jakka. Giyu and Shinobu should be enough to deal with whatever demons were lurking in that mountain. 

I personally wanted to see the progress Tanjiro had made since his graduation from the slayer trial. I had gotten a report from my ravens nearly several weeks ago about how he had bested a mutated demon on the mountain. 

Looking into the distance I felt for my marker that I had placed on Giyu and Hiraishined away in a flash of red lightning. 

I arrived standing next to Giyu who stopped abruptly in his tracks. He had been running through some trees when I had teleported to him. 

"Yo." 

He blinked at me, "What are you doing here?" 

"I'm here to assist, a Kakushi brought it to my attention that there was a Lower Moon here." 

"Tsk…" 

I grinned, "Aww not happy to see me Giyu-chan?" 

He didn't respond for a second, "Fine, I'll go find Kocho-san, you go that way. My Kasugai told me that the Lower Moon is in that direction." 

"Hai hai," I continued to joke around with Giyu, "I'll fight the scary demon for you." 

Giyu sighed, "Just try not to burn down the forest." 

He ran off in the opposite direction after making me smirk. 

'What a killjoy, oh well, makes fucking with him so much more fun.' 

I ran towards the direction Giyu had originally been going. Slowly the sounds of a fight grew louder. I broke through a clearing and spotted a boar masked individual fighting a rather large demon. 

"Get back here and let me cut you!" The boar headed slayer shouted. 

'What the fuck?' I stopped and observed the fight for a moment. 

The masked slayer was obviously a female judging by her wrapped chest. She was already injured as blood was pouring out of the nose of her boar mask and she had various cuts on her body. 

The demon roared and charged at her, she performed an impressive display of acrobatics and landed a blow to the demon's neck. She let out a shout of anger and started hammering her second sword into her first. 

The jagged looking blade slowly started going through the demon's neck. Finally with one last hit, her sword finally cut through the demon and she collapsed next to it just as it began to turn to ash. 

As I stepped towards the defeated demon and injured slayer she jumped back up on her feet and pointed at me. 

"You! Who are you!?" 

"Still got some fight in you eh?" 

"Don't ignore me!" 

"Heh," I chuckled, "My name is Akimitsu Uchiha, Hashira of the Sun." 

"Fight me Akimata Uchoka!" 

My eyebrow twitched, "Hn, you can't even get my name right, why should I fight you?" 

"Are you scared Akikoki Uchara?" She growled. 

'She has to be doing this on purpose.' 

"Listen, have you seen the Kamado kid?" 

She let out a rather undignified sound for a girl and rushed at me. 

"I'll never tell you where Kamaboko Gonpachiro is until you fight me!" 

Sighing I sidestepped her clumsy attack and pulled out some rope. The masked slayed yelped in surprise when I blurred away only to reappear behind her. 

"So fast!" She exclaimed before realising that I had tied her up to a tree.

Each wrap strategically placed to act as a tourniquet to her more serious wounds. I dusted my hands off and stood behind her. 

"Where's Tanjiro?" 

"I won't tell you where Kentaro is." 

"Hn… you brought this on yourself." I put my hand into a tiger seal. 

"Konohagakure hiden taijutsu oji: sennen goroshi!" 

The boar masked girl struggled in her bonds, "I- what are yo- KYAAAA YAMETE!!!!" 

I pulled my fingers back from where I jabbed them, the boar masked girl was whimpering. She swayed back in forth in the air from the force of my attack. 

"Moh… no one one will ever take me as their mate." She groaned out. 

"…" 

"Where is Tanjiro?" 

"I-I I'll never tell you pervert!" 

I sighed putting my hands in the tiger seal again.

"No! Wait! I mean, he's in that direction!" The boat masked girl twitched her body towards a thicket of trees. 

"Now was that so hard?" 

She growled at me as I started running to where she had motioned. 

"You get back here and let me punch you Ugaki Achiko!" 

'How do you even get names so messed up?' I thought to myself as I ran. 

[Scene Break]

Kamado Tanjiro breathed heavy, his wounds staining his uniform and haori with red. His broken nichirin blade clenched tightly in his hands. Nezuko was tangled up in Rui's webs also bleeding from cuts all over her body. 

'Damn it! Nezuko, Takeo, Hanako, Shigeru, Rokuta, Kaa-san, Tou-san… I can't fail here, I have to succeed!' 

Clenching his teeth Tanjiro prepared to make one final dash at Rui who stood a few dozen feet away from him staring at him emotionlessly. As he got ready to attack, Rui suddenly spoke as he raised his hand. 

"Don't tell me, you think you can actually defeat me?" 

Rui tightened the threads around Nezuko making the demoness cry out in pain through her bamboo gag. Tanjiro felt anger flare in his body.

'Total Concentration!, I have to beat him with my next move.' 

With that, Tanjiro charged as Rui sent out tendrils of hardened spider webs at him. Tanjiro batted away the threads with his broken sword, gracefully moving forward as he called out his technique. 

"Water Breathing: Tenth Form! Constant Flux!" 

Rui let out a startled gasp, Tanjiro got closer and closer. The demon growled and prepared to unleash a devastating attack. 

"Demon Blood Art: Cutting Thread Cage." 

The demon said the name of his attack, the former white threads turned blood red as Rui infused them with power. 

"I have no use for you anymore," The demon looked at Tanjiro dispassionately, "goodbye." 

With a twitch of his hands the blood red threads closed in on Tanjiro who's eyes widened in horror. 

'No… I'm sorry everyone.' 

As he was about to close his eyes and accept his fate Tanjiro felt the temperature rise up around him. A calm voice echoed through the clearing making him open them again. 

"Are you just going to give up boy?" 

Tanjiro and Rui looked at the man who had just arrived. The man looked at the two of them with a bored stare. The man was wearing a black haori with a red and white fan depicted in the back. A sheathed blade was in the man's hand. 

'No he's right… I can not give up here!' 

Memories flashed through Tanjiro's mind, his father teaching him the families traditional dance, a dance that was said to ward off evil. Resolve filled his body as he tensed his muscles, flipping through the air Tanjiro shouted. 

"Hinokami Kagura! Dance." 

He felt his blade heat up as he cut through the seemingly indestructible threads that Rui sent out. The spider demon's eyes widened. 

'Don't stop, even if he cuts you… you have to defend Nezuko!' Tanjiro shouted at himself in his head. 

He closed the distance between him and Rui fast, he knew that his body couldn't take the strain it was going through but he pushed forward. Shouting in defiance he swung wildly at Rui making the demon dodge and move away. 

Meanwhile Nezuko, deep in her subconscious, saw a vision of her mother telling her to protect her brother. She opened her eyes slowly and saw Tanjiro fighting a demon. Anger filled her veins as she activated a power she didn't know she had. 

Tanjiro's blade exploded in fire as he seemingly cut off the demon's head. Seeing that the danger was gone, Nezuko faded back into unconsciousness from the pain. She failed to see the demon reattached its head and started walking towards her fallen brother. 

Tanjiro huffed and puffed, his arms hung weakly at his side. The relief he felt after seemingly defeating Rui fading when the demon reattached his own head. 

"That was close, thankfully I separated my own head before you could cut it." 

The demon slowly walked towards him, malice in his eyes. Tanjiro felt tears run down his face.

'I-I failed.' 

As he accepted his fate, a voice rang out again. 

"Good effort kid." 

His eyes widened. 'How could I have forgotten! No I have to tell him to run, this demon is strong!' 

"Wait your turn mortal." Rui hissed. 

"Oho? Brave words there demon brat." 

Tanjiro's eyes widened as he turned to face the man slowly approaching him and Rui. The man still looked calm as ever. Rui sent an attack at the man but the threads harmlessly disintegrated, shocking Rui and Tanjiro both. 

"Very well, you shall die too human scum." 

"Ho? You're approaching me? Instead of running away you're coming right to me?" The man drawled as Rui stepped forward. 

Tanjiro wanted to tell the man to run, but the words were lost in his throat. 

"Tell me your name arogant human, I want to know who I am about to kill?" 

"I'll humour you this once demon brat, seeing as that you're about to die… my name is Akimitsu Uchiha, Hashira of the Sun, wielder of Ryujin Jakka." 

Rui froze, "No, you lie." He spat out in denial. 

"Hmm, too late for regrets." Akimitsu shook his head before slowly drawing his sword which gleamed dangerously. 

Rui raised his hands to attack again. "DIE HUMAN!" 

"No you… All Things in the Universe, Turn to Ash… RYUJIN JAKKA!" 

Rui along with a solid mile of forest burned to ash in an instant. The demon didn't even have time to scream as he was erased by a wave of blistering fire. Tanjiro gaped as did several observers hidden in the trees. 

The man slowly sheathed his blade, the temperature returning to normal. Tanjiro looked at the man in shock and awe. 

"I feel like a hypocrite for calling out the names of my attacks but oh well, it's badass when I do it." 

Tanjiro fainted.