My Upgrades Are Invincible

With the abrupt death of Doma by Kanae and Shinobu, the other upper moons seemed to realize there lives were genuinely at risk and seeing as this wasn't canon, Muzan hadn't purged the lower ranks of upper moons so the weaker upper moon six were actually a decent threat to the other Hashira but with it being one upper moon versus two Hashira with Gyomei taking on both Hantengu and Gyokko simultaneously and was abusing his unorthodox spiked ball on a chain attached to a large axe combination to keep them separated and even as Hantengu split his bodies or Gyokko teleported between large pots that appeared on the battlefield. Gyomei was simply too strong and the weapons chain extended his weapons reach of influence that no other demon slayer bothered to interfere out of the fear of distracting Gyomei's dance of death with the two upper moons.

But I knew it was likely he wouldn't be able to kill them all alone there weird immortality mechanics so as soon as I destroyed Doma's head and threw the rest of his corpse into my space ring for me to later fuse into some weapon later on, I immediately flash stepped with my necklaces space skipping steps between the battle and punted the highly durable large pot Gyokko was currently hiding within and taking pot shots at Gyomei with high pressure water lances and more annoyingly was his weird demon fishes and tentacles he was shooting out of the pots scattered across the battlefield which was currently battling the lower ranked demon slayers and making opportunities to for other demons to kill the lower ranked demon slayers.

But Hantengu even with his weird clones weren't causing as much chaos that's why I decided to target Gyokko first.

Unfortunately, I didnt catch the demon before he became serious, and he was already clad in scales literally harder than diamond supposedly but even as the monstrous form proudly went onto explain how he was going to drown me in his water pot I allowed him to form the water pot around me knowing he had to be out of his teleporting pot system and just as he jumped out and closed his fists to spring his trap of a massive water pot forming around me and crushing me like I was extremely deep under water. A massive explosion of steam and black flames blew Gyokko away from his pots and horribly burned him as regardless of him being able to have diamond hard scales, didnt protect him from boiling from within.

"I don't have time for pissants like you... I want to kill Muzan and Kokushibo, but I don't you freaks wreaking havoc amongst the lower rank demons' slayers." I grumbled and then with a vicious kick to the collapsed Gyokko's side he flew straight up into the air and I had little interest in trying to cut through literal hard as diamond scales so I flew up at my maximum speed and as I reached the form of Gyokko who was coming to stop from me kicking a dozen meters into the air I brought my knee up and with a loud crack, Gyokko's spine shattered and the demon vomited blood as the he was shot higher into the sky.

"You can thank Endeavor and Rock Lee for this idea and your method of execution!" I yelled flying briefly past him just to get around to grab him by the legs and then lock my feet around his head while using my flames to launch ourselves at the ground while wreathed in my most potent flames while spinning and baking his head directly with the jet boots.

A ground shaking explosion was the answer to my action of using Gyokko as a drill and the potent flames combined to create a dozen meter deep hole into the ground and luckily I was paying enough attention to divert my ghetto Lotus into a cluster of demons hanging on the edge of the battle and using long distance blood demon arts to attack the demon slayers.

Needless to say, even though I didnt cut his head off with a Nichirin Blade I was able to store away the mangled corpse of Gyokko and then the screaming forms of the slowly recovering demons were whisked away as Nakime opened a doorway into her dimension and knowing how she was literally the biggest reason I came here to Demon Slayer I dashed into the door as she attempted to move the hurt demons to another side of the battlefield away from me so they could continue to attack over long distances as they recovered.

'Now to try to find Nakime and the Kamado children who snuck in here...' I thought while mentally promising to tan Tanjiro and Nezuko's hides for daring to sneak in here.

Honestly the trash demons Nakime pulled in and moved to apprehend me as I delved deeper into the infinity castle were worthless and didnt take more three swings of my sword at the most to kill so I didnt even bother to collect their corpses as I was flying between the structures making up Nakime's reality marble until I finally heard the sounds of combat in the distance.

But after several building kept getting in my way, I decided to go with my backup plan which was to coat space blades in black flames and send them everywhere and it took me emptying my mind of half its mana for finally her reality marble started to collapse internally as a heart wrenching scream rang out and the unmistakable sounds of a guitar's strings to violently snap apart.

"Here she comes..." I muttered and I was right as Nakime dove at me through a door that appeared upon its walls and I could only sigh as my sword easily took her head off her shoulders as she wasn't the much stronger form she had when Muzan fed her massive quantities of her blood after the Hatengu and Gyokko's original deaths.

In other words, she was much weaker, and her structures still hurt her when destroyed which is why I destroyed so much of her reality marble.

"Giyu! Guys where are you!" I screamed as the reality marble started to collapse and thankfully I heard yelling in the distance and franticly flew over.

As I was flying over I saw the doors from Nakime's reality marble opening and showing the odd interiors of various buildings around Japan from the looks of things and more predominantly it showed flashes of the battle going on outside and as I reached where the voices where coming from I saw Giyu binding up the wounds Inosuke and Tanjiro had.

"They going to be, ok?" I asked instantly throwing Nezuko over me should with Zenitsu in my right arm as Giyu and Tanjiro held onto my left shoulder and arm while cradling the more grievously injured form of Inosuke between them.

Giyu calmy answered as I franticly flew between the collapsing building's trying to find a door to exit the reality marble from "He has several broken ribs, and his arm has broken protruding bones which were the blood is from and was caused by the demon hitting him with a marble pillar."

'Kinda surprised he survived that to be honest...' I thought before luckily catching a wall with an open door leading to the battle outside on fire, so I yelled out. "Hold on I got our exit!"

Even as Zenitsu screamed about how I was going to kill us as I blasted forward and flew around sever pieces of debris both Giyu and the Kamado siblings had total faith in me other than squeezing onto me instinctually.

But their faith was proven correct as I triumphantly flew out of the reality marble and Giyu instantly jumped off my shoulder and like a baddass in his drop he decapitated a demon and used its corpse to break his fall.

"You guys stick to fighting the weaker demons don't make your mother cry!" I ordered and blasted off to join Yoriichi in the climax of the battle, happy with getting Nakime's body and wanted this battle to end without more demon slayers dying as I saw literally hundreds of the black uniform clad people's bodies littering the ground as I Muzan and Kokushibo's large are of effect blows carved there marks into the surroundings and hit both friend and foe as they attempted to kill the man they both feared and hated the most throughout their long lives.