Enmu was on the ground with his body beginning to disintegrate! 

Enmu: Am I dying?! NO! This can't be! I never even used my full strength! I didn't even devour a single human. My plan to fuse with the train and eat everyone failed! This is all that Hashira's fault! He cornered and pined me down! Those troublesome girls were fast with their skills! Not to mention that demon girl. I can't believe it! Why would a demon work for Demon Slayers?! ANd ... that brat. I should have killed him. This is a nightmare! It's always us lower level demons that die. The Upper Moons, Kokoshibo, Doma, Akaza, Hantengu, Gyokko, Gyutaro, and Daki, they've all buried hundreds and hundreds of Demon Slayers. Hell, they're so powerful they've killed Hashira! Even though Lord Muzan gave me his blood, I was not on any of their levels! 

With that, he completely disentigrated. 

(Y/N): You did well Tanjiro, I'm so proud of you! 

You healed him up,  and then- 

???: YES! WELL DONE YOUNG KAMADO! 

(Y/N) and Tanjiro: KYOJURO!/MR. RENGOKU! 

The Flame Hashira appeared out of nowhere. 

Rengoku: That's the first step to becoming a Hashira! But there's still 10,000 more to go! 

Tanjiro: I'll do my best! 

(Y/N): What about the other passengers? 

Rengoku: Everyone else is safe. Injured, but not dead. 

(Y/N): Oh thank G- Oh no. 

Tanjiro: What is it? 

(Y/N): I sense a powerful chi. Coming this way! 

Then a figure landed nearby. 

Akaza (Upper Moon 3! He is Muzan's favorite! Blood Demon Art: Destructive Death!) 

(Y/N): THE HELL?! 

He charged for you, but before you could attack- 

Rengoku: FLAME BREATHING: SECOND FORM: RISING SCORCHING SUN! 

He cut Akaza's arm in two, only for him to jump back and regenerate!

Akaza: My, your blade is very impressive. 

(Y/N): This guy ... he's one of the Upper Moons of the Kizuki! Not only did he regenerate on the dime, but ... his power is tremendous. What's your deal? 

Akaza: I sense powerful opponents when I see one. And I already see two powerful ones before me. 

He pointed to you and Rengoku. 

Rengoku: You clearly have different values. 

Akaza: Well then, how about this? How about you both become demons? 

(Y/N): Yeah no, I'd rather die than serve someone like Muzan. And you are? 

Akaza: Upper Moon 3, Akaza. And you- 

Rengoku: I am Kyojuro Rengoku, the Flame Hashira. 

Akaza: Ooh! A Hashira! I've taken down several! Tell me something Kyojuro, why is it that your power will never be perfect? It's because you are a human. You age and eventually die. You and your friend should become demons and live forever! 

(Y/N): WHAT?! Life is a journey for humanity! I don't care if I become old, there's beauty in old guys. Old guys don't use their age as in excuse to show how powerful they are! 

You thought of guys like Roshi and Rayleigh, who are very powerful despite how old they are. 

Rengoku: Young (L/N) is right. Strength is not a word. That means much in regard to the flesh. It's preciously because we age and die that our lives have value and nobility. 

Akaza: Fine then! DESTRUCTIVE DEATH: COMPASS NEEDLE! 

A giant snowflake compass appeared on the ground as Akaza took a fighting stance. 

Akaza: I guess you'll have to die then. 

(Y/N): Not on your- 

Rengoku: No, Young (L/N)! I'll handle him! FLAME BREATHING: FIRST FORM: UNKNOWING FIRE! 

The two clashed and Akaza was knocked back! 

Akaza: You know, the other Hashira I've killed didn't use flames. Still, none of them accepted my proposal. Why is that? As someone who also walks the path of the warrior, I do not understand it! You worked so hard to build such magnificent talent, would simply let it wither away. Such a waste! It's hard for me to accept! I can't stand it. Die for me, Kyojuro! DESTRUCTIVE DEATH: AIR TYPE! 

While in the air, he unleashed powerful blows from his fists onto Rengoku, but- 

Rengoku: FLAME BREATHING: FOURTH FORM: BLOOMING FLAME UNDULATION! 

He then got in close after blocking the attack, but Akaza continued to block and counter! 

Akaza: Your speed and technique! Time will take it all away from you Kyojuro! 

Rengoku: That is normal! That is what it means to be human! 

(Y/N): Kyo- 

Rengoku: Young (L/N)! Don't! 

Akaza: Don't waste your thoughts on distractions! Concentrate everything on me! You need all your strength for me! 

Rengoku: FLAME BREATHING: FIFTH FORM: FLAME TIGER! 

Akaza: DESTRUCTIVE DEATH: DISORDER! 

Team RWBY and Inosuke soon arrived. 

Ruby: Is that Mr. Rengoku?! 

(Y/N): Yes. He's fighting one of Muzan's Upper Moons. 

Weiss: WHAT?! 

They then saw Akaza. 

Blake: That one ... he's very ... powerful. 

You then saw Rengoku, and- 

Rengoku: BLEGH! 

He was coughing up blood! 

(Y/N): NO! KYOJURO! 

Inosuke: What the hell? This guy ... he's on a whole other level. 

Inosuke was shaking in fear. He could tell Akaza eclipsed him in strength. 

Akaza: No matter how desperately you fight, it's all useless, Kyojuro. Your left eye is crushed, your ribs are broken, your bleeding heavily, they're all serious wounds. If you become a demon, you could heal everything! 

Rengoku: It doesn't matter if I die! I WILL SEE MY DUTY FULFILLED! 

(Y/N): WHAT?! 

Yang: STOP! DON'T! 

Rengoku: REMEMBER! SET YOUR HEART ABLAZE, AND OVERCOME YOUR LIMITS! FLAME BREATHING: ESOTERIC ART: NINTH FORM: RENGOKU! 

He charged at Akaza with a trail of flame going behind him! 

Akaza: DESTRUCTIVE DEATH: ANNIHILATION TYPE! 

The two clashed at high force as you all watched! 

Tanjiro: Did he- Is Rengoku- 

Blake: I don't know, I can't see anything in- 

(Y/N): His chi, it's falling. It- NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO! 

Everyone was horrified at what they saw. 

Akaza: YOU'RE FINISHED KYOJURO! GIVE IN AND SAY YOU'LL BECOME A DEMON! 

Rengoku was blacking out, and he saw a woman, his mother. 

In the past... 

Rengoku's Mother: Do you know wh you were born stronger than people? 

Young Rengoku: I don't know. 

Rengoku's Mother: So you can help those weaker than you. Those blessed with more natural talent than others must use their strength for the good of the world, for other people. It is unforgivable to use strength granted by heaven to hurt others and empower yourself. Helping the weak is the dirty of those born with strength. You must take your responsibility and do your duty. Never forget that. 

Young Rengoku: Yes, Mother! 

Back in the present... 

Even though Rengoku was near death's door, he slammed his blade onto Akaza's neck! 

Akaza: AAAAAAGH! He can still swing his sword?! 

Rengoku: AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAARGH! 

Akaza tried to punch Rengoku, but the Flame Hashira grabbed his arm with his other hand! 

Akaza: Unbelievable! He's so powerful! I have to kill hiM! I- 

But he couldn't move his arm! 

Rengoku: I WILL NOT LET YOU ESCAPE! 

(Y/N): GUYS! COME ON! 

You all charged to help Rengoku, and Akaza noticed this and let his arms get severed to escape! 

(Y/N): COWARD! 

You turned SSJ and- 

(Y/N): HINOKAMI KAGURA: DANCE! 

As Akaza ran, you appeared to him, and gave him a massive burning scar on his whole body! 

Akaza: AAAAAAAAAAAAAAAAAAAAAAAAAAARGH! 

(Y/N): DON'T YOU RUN AWAY! THE DEMON SLAYERS ARE FLESH AND BLOOD HUMANS! OUR WOUNDS DON'T CLOSE QUICKLY! LOST LIMBS DON'T GROW BACK! AND YET YOU'LL ONLY FIGHT US IN THE DARK OF THE NIGTH WHEN YOU HAVE THE ADVANTAGE! YOU'RE JUST AFRAID TO ADMIT THAT KYOJURO DIDN'T LOSE! HE IS STRONGER THAN YOU! HE SAVED EVERYONE FROM YOU! HE PROTECTED EVERYONE! THAT IS YOUR DEFEAT! 

Rengoku: Lad. That's enough. Don't exert yourself like that. Come over here. 

You walked to him. 

Rengoku: Everyone, listen. You should go to the house where I was born. There are the writings of the past Flame Hashira. My father read them often, but I didn't. So I have no idea what's written in them. They may contain the records of the Hinokami Kagura. 

(Y/N): Kyojuro, let me heal you, I can- 

Rengoku: I'm sorry Young (L/N), that won't help. I'm going to die soon. Just listen to what I have to say. I want you all to find my little brother, Senjuro and tell him to take the path that he thinks is right. And my Father, please tell him to take care of himself. Also- 

He turned to Tanjiro. 

Rengoku: Young Kamado, I believe in your little sister. I have considered her as a member of the Demon Slayer Corps. She risked her own life to protect humanity. If she risks her life to protect people, then she's a member of the Corps, no matter what anyone else says! Stand tall and be proud. No matter how eak or unworth you feel ... keep your hurt burning, grit your teeth and move forward. Don't worry over my death. I am a Hashira, it's my duty to protect junior members like you. 

You all were crying over him. 

Rengoku: You just need to keep learning and growing. Someday you all will become Hashira and proud warriors of the Demon Slayer Corps. I believe ... in ... you. 

He then saw his mother. 

Rengoku: Mother ... did ... I ... do ... well? 

She just smiled at him, as he passed on. 

Tanjiro: This is so frustrating! Every time I learn or do something new, I learn just how much more there is I don't know. I'm falling beh- 

You hit him on the head. 

(Y/N): NEVER EVER SAY THAT TANJIRO! You killed the demon! You did the most important job! We need to train! We have to be ready! Because the next time that bastard comes, it's death for him! 

Inosuke: YES! 

Everyone turned to Inosuke. 

Inosuke: HE BELIEVES IN US! SO DON'T WORRY ABOUT ANYTHING OTHER THAN LIVING UP TO THAT! CRYING WON'T BRING THE DEAD BACK! EVEN IF YOU THINK YOU'RE UNWORTHY, YOU MUST KEEP ON LIVING! 

(Y/N): Inosuke, you're crying too. 

Inosuke: N-NO I'M NOT! 

Soon... news spread out about his death... 

Shinobu: Rengoku ... I'm sorry. 

Mitsuri: Wh-WHAT?! NOOOOOOOOOOOOOOOOOOOOOOOOOO! 

Mitsuri began to cry. 

Uzui: Even Rengoku lost to an Upper Moon. 

Obanai: This can't be. 

Gyomei: May you pass on to a better place, my friend. Namu Amida Butsu. 

Sanemi: YOU MOTHER FUCKERS! HOW DARE YOU! I'LL MAKE YOU ALL PAY FOR WHAT YOU DID! 

Kagaya also heard. 

Kagaya: Kyojuro. You were an incredible young man. Soon, I'll go to the other world where you and the others have joined.