The bond between two siblings

The new uppermoon 6

Zenitsu pov:

Seems like i found kaigaku, that bastard, became a demon, a demon moon! And it forced grandpa to kill himself! And kaigaku didn't care, no matter how much kindness i showed to him, it just seems like he doesn't care.

Narrator pov:

"Why..." Zenitsu asked, "why did you do it! Kaigaku!!" Zenitsu was in a fit of rage. "Hah!! If its about grandpa then I don't care!!! He paid attention to someone like you! Who only knew One form! Unlike me to mastered all the forms!" Kaigaku said while laughing. "You piece of shit.... You don't even deserve to be alive! I will kill you tonight!" Zenitsu said immediately getting into position. "HAH!!! you think you can kill me?!?! With just one form?! Hahaha! What a joke!!!" Kaigaku said while drawing out the blade on his back. "Breath of thunder, first form: thunder clap and flash, 6 folds!!" Zenistu said as the ground began emitting lightning and with one quick dash but kaigaku knew all the forms "Breath of thunder, second form: rice spirit!" Kaigaku unleashes five electrified arching slashes all in a single moment. This force Zenitsu to stop in his tracks as he got knocked back and coughed up blood, "breath of thunder, third form: thunder swarm" Kaigaku surrounds the Zenistu with powerful waves of electricity and sword slashes that slice up the Zenistu in all direction. "Breath of thunder first form: thunder clap and flash" Zenitsu managed to save himself but he tot severely injured.

"The fact that your still alive is impressive!!" Kaigaku said "breath of thunder, Fourth Form: Distant Thunder" Kaigaku generates powerful lightning strikes in several directions with his blade from a far distance. But luckily the attacks missed as Zenitsu was barely able to dodge but doesn't mean he didn't get wounded from the attack, but it was only a flesh wound. "Breath of thunder, Fifth Form: Heat Lightning" Kaigaku unleashes a powerful ranged electrified sword slash upwards that burns the flesh of his opponent. Zenitsu was still alive but he was now standing over an edge with a huge drop that he wouldn't even be able to see the bottom. As three more slayers appeared and saw kaigaku with his eyes saying uppermoon 6 "Breath of thunder, Sixth Form: Rumble and Flash" Kaigaku releases a series of strong ranged electricity attacks that strike his opponent from multiple directions. As Zenitsu was hit by an attack as he falls into the drop and the other slayers were killed immediately.

Zenitsu remembered something, as he saw his grandpa and heard his grandpa speak "Listen Zenitsu, don't you dare die on me. Your strong Zenitsu, your stronger than you look! I love you so much, you were like a son to me, now show them what you got!" Then suddenly as kaigaku was about to leave thunder began emitting from where Zenitsu should've fallen and died. "He's still alive?! Hah!! Dont worry! You'll join grandpa very soon!" Kaigaku yelled as he pulled out his blade, suddenly in a blink of an eye "breath of thunder, seventh form: FLAMING THUNDER GOD!" Zenitsu said The personal creation of Zenitsu Agatsuma. The user dashes forward at blinding speeds superior than even his Godspeed technique and unleashes a singular forward slash, towards kaigaku, so fast that he couldn't even react when in one moment, he was hit by a sudden attack with with what seems to be a dragon made out of thunder while kaigaku's head was chopped off.

Kaigaku pov:

What was that?! I couldn't even react!!! Did i actually get hit?!?! By him?!?! My body, its turning into ashes, "What form was that?! Breath if thunder inly has 6 forms!" I yelled as Zenitsu replied "its a form i made it all by myself" As we both fall into the pit, i knew that he was going to die with me! "Hah! Your gonna die anyway!!" I yelled

Narrator pov:

As they were both falling Yushiro appeared and said "no... only you will die right here" before jumping up and saving Zenitsu by carrying him on his back and regrouping with a group of slayers. "Did uppermoon 6 actually die bu this guy?" Asked murata as yushiro nodded as he began tending to Zenitsu's wounds.

Meanwhile

As sanemi and tanjiro slaughtered the life out of the demons they began running through the infinity fortress "I cant believe I'm even working together with you of all people" said sanemi while tanjiro only laughed a bit then they saw genya and mitsuri fighting together against two winged demons. "It must be an upper moon" said tanjiro "lets help them out!" Tanjiro said then suddenly a room moved and pushed tanjiro away and into a door "TANJIRO WHERE THE HELL DI YOU THINK YOUR GOING" sanemi yelled "JUST HELP OUT GENYA!" Tanjiro yelled back.

Sanemi immediately went to the platform where both genya and misturi are and decapitated one of the demons with a form. "Hah! Now come at me you feathered piece of shit!!" But suddenly another demon appeared while the demon sanemi killed grew back his head. "Seems like were going to have to cut all their heads off at once" said misturi while whipping out her blade which was like a whip. Then one of them got shot down and flew back up for his wounds to heal. "When did you learn how to shoot a gun?!" Sanemi asked genya who was reloading his gun. "Since i began fighting these bastards?" Genya replied. Then the trio got ready to fight uppermoon 4 as one them said "what a pest"

Tanjiro on the other hand who landed through a door and landed on his feat, looking forward and there he saw him. Muzan... "ah... kamado tanjiro, the descendant of yoriichi and the student of Kokushibo" muzan said while drawing out his tentacles "muzan... the king of demons and the bastard who murdered my family" Tanjiro replied while drawing out his blade, he let his blade grow bigger. "I have a proposal for you, become a demon moon, i do need to replace Uppermoon 1 and I can't think of a better person to fill the rank as you are my former uppermoon 1 student" muzan was saying but tanjiro just said "have you gone bat shit crazy? My answer will be a no" as muzan just chucked and said "what a shame" as he began sending his tentacles to stab tanjiro "breath of the moon Eleventh Form: Cosmic Infernadoes" Tanjiro twirls his blade to create multiple chaotic structures of pure slashes that bear striking resemblance to actual tornadoes/cyclones that slowly chase down their foes. In addition to that, the chaotic blades emanating from the slashes act much like debris from the respective disaster. It immediately destroyed his tentacles only for them to heal in a matter of seconds as he sends more this time tanjiro failed to protect himself as he got severely injured "breath of the moon, Fourteenth Form: Catastrophe, Tenman Crescent Moon!"  Tanjiro swings his sword and creates a chaotic vortex of powerful omni-directional slashes that destroys whatever is caught up within its attack radius. Injuring muzan but they healed in a blink of an eye. Some of tanjiro's wounds weren't healing at all, "breath of the moon, Eighteenth Form: Waxing Forth, Burning Sky!" tanjiro raises his sword towards the sky and swings downward raining down a plethora of chaotic projectiles, the projectiles actually cut off some of muzans limbs and his tentacles but they all healed in a matter of seconds then tanjiro was up close to him suddenly "breath if the moon, Twentieth Form: Cataclysmic Calamity, Lunar Extinction!" Tanjiro unleashes a devastating barrage of slashes and stabs in all directions with the swords emanating from his body within an extremely large radius that decimates anything it makes contact with. A huge explosion was occurred on the fortress, it caught the attention of many slayers and the hashiras even the uppermoons.

As the dust cleared for tanjiro, the room was mostly destroyed but suddenly a hand punches straight into tanjiro's chest, and there he saw muzan regenerating in seconds "you remind me so much of Kokushibo, shame you couldn't be an uppermoon." Muzan said as he began absorbing tanjrio while tanjiro was screaming in pain. But at the right moment tanjiro used a form to escape from muzan "breath of the moon, Ninteenth Form: White Crystal, Moonbeam!" Tanjiro pulls his enlarged flesh sword backward and greatly thrusts the blade forward creating an extremely long beam of chaotic slashes in the direction his sword faced. Destroying muzans body a bit and cutting off his limbs and tentacles as tanniro jumped back and found himself standing across muzan from a distance. As they both stared tanjiro was filled with rage, as his blade grew bigger than before looking like kokushibo's blade.

To be continued

Yo! How was this chapter? There will be a few more chapters left as this series is coming to an end!

Taisho secret 1: while tanjiro was waging war against muzan, other hashiras found themselves against the uppermoons
Taisho secret 2: yushiro has been laying down his blood demon art and rallying slayers together. With it the new ubuyashiki and his last two siblings are able to control the fortress.
Taisho secret 3: honestly i feel like breath of thunder is underrated.