Yang: Hey Blake, Gyomei and I will deal with this fucker. Why don't you help Sanemi? 

Blake: Right! 

She went to stand by Sanemi's side. 

Yang and Gyomei prepared to fight Kokushibo. 

Kokushibo: These two, it looks like they use their upper body strengths to fight. 

Gyomei took a deep breath, and the breath he exhaled let him throw his flail with ease! 

Kokushibo dodged. 

Kokushibo: MOON BRE- 

But then the axe was thrown and Yang was riding on it! 

Kokushibo: WHAT?! 

Yang: FISHMAN KARATE: FLAMING SHARK ARABESQUE FIST! 

She used a flaming Fishman Karate punch, and then Gyomei came in with- 

Gyomei: STONE BREATHING: SECOND FORM: CELESTIAL SURFACE SMASH! 

The flail came forward and the chains wrapped around Kokushibo's neck, even taking the sword in! 

Kokushibo: I ... can't break these ... chains! 

He then cut off some of his hair to escape! 

Yang: HEY GYOMEI! LOOK OUT! 

Kokushibo tried to decapitate Gyomei, but the Stone Hashira dodged and then he went above Kokushibo and swung the flail at him! 

Then as Kokushibo dodged- 

Yang: GOT YOU! ASSHOLE! TIGER SHATTER FIST! 

She punched the sword, and it broke in two! 

Kokushibo: MOON BREATHING: SECOND FORM: MOONLIT PEARL FLOWERS! 

Gyomei: STONE BREATHING: FOURTH FORM: RHYOLITE: RAPID CONQUEST! 

The two went at it with their attacks and Yang grabbed the blade and rammed it into his neck! 

Kokushibo: Everything that breaks will regenerate right away. Attacks are useless, pitiful humans. 

His sword regenerated, and then he knocked Yang back. 

Yang: DAMN IT! 

Gyomei: We have no other choice. I wanted to save this for when we faced Muzan. But if I fall here, then it will be much harder. I have nothing to lose in using it here! 

He activated his Demon Slayer Mark! 

Yang: Heh, then let's go all out! KAIOKEN TIMES 50! 

Muichiro at that moment pulled himself free! 

Blake: MUICHIRO?! 

She rushed to him. 

Muichiro: Just ... forget about me. I'm not in a good condition to fight. It will take me several hours to stop the bleeding. I'm not blessed with the physique of someone like Uzui. 

Blake: No, we need all we can against him. 

Genya: HEY! YOU TWO! 

Blake: What is it Genya? 

Genya: I don't want to be a bother, but I need you to knock my torso over. 

Blake: I'm surprised you're still alive at this point! 

Genya: Look, I need the Upper Moon guys' hair! 

Blake: His hair? 

Genya: I'll do whatever I can to help Bro! 

Blake: I'm still fine. But if you two want to- 

They both seemed determined. 

Blake: Then let's back them up! 

Kokushibo: I see, you're marked too. How unfortunate. 

Yang: Huh? 

Gyomei: What do mean by unfortunate? 

Kokushibo: I suppose by your looks, you are 27 more or less. 

Yang: And why are you saying that? 

Kokushibo: Because every Demon Slayer with the mark dies before reaching the age of 25. 

Yang: WHAT?! 

Kokushibo: That is right. Even if the mark appears, and you increase your power, a Demon Slayer is only living on borrowed time. When you're past the age of 25, that means you are on the time of dying. 

Gyomei: I don't have any regrets. I only knew. There is no guarantee that I will live to see tomorrow. What is there to regret about my life now? You can't become a Hashira with that kind of half-hearted resolution. 

Yang: Nice one man! 

Kokushibo: Yet you all can preserve your techniques by becoming demons. 

Yang: No fucking way man. I prefer to die as a human. Life rocks no matter what sucky things come your way. Besides, you sold your soul to Muzan, so you're his lackey now! Besides, there have to be people who might have lived past 25 and had the mark. 

Gyomei: Xiao-Long speaks the truth. There has to have been an exception. 

Kokushibo tensed up and sweated. 

Yang: Heh, looks like we're right on the money Gyomei! This guy knows something we don't! 

He tried to attack, but they started to go at it with him! 

Sanemi stood up as his Demon Slayer Mark activated, taking the form of a spinning wind blade on his right cheek. 

And then he jumped in to attack! 

Yang: About time Sanemi! What kept you? 

Sanemi: Hey, I'm a Hashira, but I'm not fucking invincible! 

Yang: Eh, that's true. 

Sanemi: Hey, Himejima, sorry I'm late! But now with me in the fray, we can do this! 

Yang: HELL YEAH WE CAN! GIVE IT UP! I got two Hashira helping me, so that means you're going to lose! 

Blake and Muichiro helped Genya eat Kokushibo's hair. 

Muichiro: Genya, are you alright? 

Blake: Please don't lose yourself. 

As Genya swallowed the hair, he heard- 

Genya: That's ... Muzan's voice! 

He heard Muzan's voice in his head. 

Muzan: Kokushibo, how many Hashira have you beaten? Don't let them come yet. 

Genya: Got to hold it together. They need me. 

Back on the battle, Yang was punching Kokushibo with blow after blow, though he attacked with more Moon Breathing techniques, Gyomei and Sanemi intercepted! 

The three were easily working together with a very quick flow! As if they practiced! 

And then- 

Yang: FISHMAN KARATE: FIERY DEMON BRICK FIST! 

Sanemi: WIND BREATHING: SEVENTH FORM: STRONG WIND: TENGU GALE! 

Gyomei: STONE BREATHING: FIRST FORM: SERPENTINE: TWIN POLES! 

Kokushibo was getting torn up! 

Yang: WE'RE DOING IT! WE'RE ACTUALLY KICKING THE ASS OF UPPER MOON 1! 

Sanemi: DON'T LET UP YET XIAO-LONG! WE STILL HAVE TO CUT OFF THIS FUCKER'S HEAD! 

But then- 

Yang, Sanemi, and Gyomei: AAAAAAAAAAAAARGH! 

They had wounds appear on them. 

Kokushibo: ALl you did was tear off my kimono. Not even I would die from that. 

Kokushibo turned around with his upper body exposed and his blade now with multiple blades on it! 

Kokushibo: Once I kill all of you, everyone else will be defeated easily! MOON BREATHING: SEVENTH FORM: MISFORTUNATE MIRROR: LUNAR SHINE!

He unleashed powerful waves across the ground! 

Yang: SHIT! 

She used Haki to defend, but still took some damage! 

Gyomei and Sanemi were taking heavy hits though! 

Kokushibo: MOON BREATHING: EIGHTH FORM: LUNAR OUROBOROS! 

A massive attack came their way as Yang smashed the ground in order to get Gyomei and Sanemi out of the way, but then- 

Kokushibo: MOON BREATHING: NINTH FORM: DESCENDING MOON: PERPETUAL PHASES! 

He just kept attacking and attacking! 

Sanemi: He's not letting up! 

Kokushibo: MOON BREATHING: TENTH FORM: PIERCING PHASE SLASH: IVY MOON! 

But then- 

???: SHADOW BREATHING: NINTH FORM: DARK MOON! 

A vale of darkness appeared and then the slashes and Kokushibo were all hit by a plethora of dark slashes! 

And then a cloud of mist appeared as well, and Yang, Gyomei, and Sanemi were saved by Blake and Muichiro! 

Yang: HA! THAT'S MY KITTY! 

Kokushibo: Her! 

Blake: EVERYONE TOGETHER! 

Blake, Muichiro, Yang, Gyomei, and Sanemi all charged in on Kokushibo! 

Kokushibo: MOON BREATHING: FOURTEENTH FORM: CALAMITY: HEAVEN'S FULL CRESCENT MOON! 

He did a massive circular attack! 

Blake: KEEP PUSHING! 

Suddenly Sanemi did his whirlwind attack as Gyomei blew off a large chunk of Kokushibo's shoulder and then- 

Yang: HAAAAAAAAAAAAAAAAAAAAAAAAAA! 

Yang punched a hole into his chest and Blake and Muichiro both stabbed him! 

Kokushibo: FOOLISH! MOON BREATHING: SIXTEENTH FORM- 

However, bullets were fired at Kokushibo! 

And then a tree grew out of him! 

Kokushibo: AAAAAAAAARGH! 

Genya had used his gun, which was now in a demonic state to fire bullets into the Strongest Upper Moon! 

Kokushibo: Damn it! I can't move! He must have eaten my hair in order to absorb parts of me! I don't believe this! This is just like- 

Four Hundred Years Ago... 

Kokushibo saw an old man. His brother. 

Kokushibo: Yoriichi. How are you still alive? You should be dead. Dead before the age of 25. How are you the only one still alive? 

Yoriichi: It's a shame, brother. 

He began to cry. 

Kokushibo was filled with anger and resentment. 

As he tried to attack- 

Yoriichi did a quick slice attack, and Kokushibo's neck  bled heavily! 

Kokushibo: You were the only exception to the laws of the world. You lived your life with the favor of the Gods on your side. I hate you, and I want you dead! 

But the next attack never came. Yoriichi died a natural death from old age, as he stood on his feet. 

Back in the present... 

Blades burst out from Kokushibo's body, and he attacked everyone, only for- 

Muichiro: AAAAAAAAAAARGH! 

Muichiro's sword turned red and the blade thrust through! 

Kokushibo: ARGH! THE BLADE TURNED RED! AND NOW ... MY BODY IS ... IT'S LIKE IT'S ON FIRE! And my techniques aren't working! Is it because of the tree?! This blade is like Yoriichi's! 

Yoriichi's Words: Brother, we are not as big as you make us out to be. We are nothing but a small fragment in humanity's long history. Someone who could very well surpass our talents may be a crying baby at this moment. They are going to arrive at the same place regardless. There's no need to worry. We should just reach the end of our lives feeling nothing but ease. One day, the children who will be born into this world after us will surpass us to even further heights. 

Yang: IT'S OVER!!! 

Sanemi and Gyomei's weapons slammed onto Kokushibo's neck, and then- 

Yang: DIE YOU MOTHERFUCKER! 

Yang punched the blades, and- 

Kokushibo was decapitated! 

Upper Moon One, had fallen! 

Kokushibo: This ... Is this why I lived for a hundred years? Did I really want to be stronger so much that I ate all those humans? No ... I just ... I just wanted to be like you ... Yoriichi. 

Kokushibo's body disentigrated, and all that was left was his torn kimono, and a small flute. 

Yang: FUCK YEAH!! YES! WE FUCKING WON! HAHAHAHAHAHAHAHAHA! 

Yang hugged Blake, and they both kissed happily! 

Genya turned away as Sanemi looked at him. 

Genya: Bro, I'm sorry. Back then I blamed you for ... what you did to Mom. I'm sorry for being a burden to- 

Sanemi hit him. 

Sanemi: (crying) YOU FUCKING IDIOT! YOU NEVER WERE A BURDEN TO ME! NOT EVEN ONCE! 

He hugged his little brother. 

Sanemi: Don't even fucking thing about that, you hear me?! You're my brother! I could never hate you! 

Genya: (crying) Bro ... thank you! 

Muichiro watched and he could only think about his brother. 

Muichiro: Yuichiro. 

Gyomei: Eveyrone, raise your heads. 

They turned to the crying monk. 

Gryomei: it is not over until, we defeat Muzan. 

Back at the remains of the Ubuyashiki mansion... 

Kiriya: DAMN IT! Tamayo is not holding out! Muzan is going to recover! 

Back at the Infinity Castle... 

A bunch of the Demon Slayers found where Muzan's Flesh Cocoon was! 

Demon Slayer: Now's not the time to stand by! We have to be of use to the Hashira and the- 

But Muzan broke out! 

And that one Demon Slayer, Muzan ripped his head clean off! 

Demon Slayer: IT'S MUZA- 

Muzan tore the man's throat to shreds! 

And then he went on a bloody massacre! 

The Demon Slayers had their limbs torn, strangled with their own intestines, their vitals shoved down their mouths, their brains ripped out, their hearts smashed, their bones coming out, and even worse, some were still alive, even though Muzan had taken their ears, tongues, and/or ears! 

Muzan: When you live for over a thousand years, you lose that feeling of eating delicious food. But now that I'm saving, everything I eat actually tastes marvelous. You actually brought me all this food to help me recover. I should thank you Ubuyashiki. 

He then held up Tamayo's head. 

Muzan: So, Tamayo, it seems that your drug didn't really work. 

Tamayo: Today ... is ... the day ... you fall ... into hell. 

Muzan: Hundreds of people have spewed out those same words at me. Yet they just won't come true. It's sad really. 

Tamayo: Give ... my husband ... and children ... back. 

Muzan: Very well then. Just die right here and go to the family you killed. 

With that, he devoured her head in one gulp, biting and chewing on the flesh and eyeballs. And he enjoyed it all! 

Muzan: Not a single of them. Not the Lower Moons, and not the Upper Moons. All of them were useless idiots! If you want something done- 

He smirked like the devil he is! 

Muzan: YOU DO IT YOURSELF!