Ok, before I start the story. Thanks to Iskandar06 for saying that I upplord the wrong chapter for the story. I was tired and had a headache.

Rengoku POV

Rengoku face attack after attack. The demon wouldn't let him rest even for a second. Rengoku has fought against over a hundred demons in his life, but not many use a sword or were close to a Hashira's level of sword technique. But his opponent weren't the only things he was worried about. It's also the bow Demon, but mostly his new ally. He impressively used the Flame Breathing Fifth Form Flame Tiger with a skill equal to himself. He had questions about it, but he mostly wondered what happened to him.

After young Izou had used the Flame Tiger he had collapsed to the ground, did he do something wrong when he did Flame Tiger? No. The swordsmanship was perfect. His body? Does he have a sickness then? No, I feel like I should have noticed it sooner. I can only think of one thing, he's not used to Total Concentration Breathing.

Izou POV

FUCK FUCK FUCK! I can't breathe, if I don't do something soon I think I'm going to die!.

That's when Izou remembered a way that can fix his problem. The problem was that he copy it from Nightingale. And it looked like it hurt like hell, and she did it to another person.

Fuck, I have no other choice do I ? With that, he tightened his stomach and opened his mouth, slapping his mouth. The air in his hand pushed into his mouth and for a moment it created a pressure that got down his throat and managed to open up one of his lungs. Izou coughed up more blood before he could get his breath back.

He turned to face the fight and saw that it went on without him. Again, he tried to find a weak spot in the demon's sword style. But he had a problem, he was almost exhausted. With the injuries from earlier and the one from his fight earlier, his options started to run out.

He stood up. Ignoring the pain all over his body, blood ran down to the ground. He holed the blade towards the demon, and it was dan he saw it. The demon reacted much slower, she was still fast, but not as fast as before.

She needs mana in order to regenerate. If I can get her to use the same attack as before, she won't have enough left to regenerate. But how do I get her to use it? She's already in power saving mode.

Izou looked around and saw The Archer Demon from before, and an idea began to be created in his head. But he need a way to kill him. Izou thought about how but couldn't think of anything. So he's just going to bluff.

Izou withdrew his sword and ran towards the demon who was still sitting in shock watching the fight. Izou let out all his bloodlust. Everyone looked towards him, and Yano tried to react but couldn't create an bow in time.

Mukago and Rengoku stopped their fight and checked where the bloodlust was coming from. Mukago saw Izou about to cut off Yano's head and something in her moved.

Because of having her secret revealed and the sudden support of someone who wasn't one of her brothers, it had awakened something in her. All the feelings she threw away a long time ago thanks to being girly. It came back and the realization that she will never meet her brother Yashin again, and seeing her last family member about to have his head chopped off brought back a feeling that she hasn't felt since the night she became a Demon. Fear.

"NO!". Rengoku was forced to jump back when the sword of his opponent exploded with a red light. With a weaker, but faster attack came towards Izou and Yano. With a Reduced Earth, Izou managed to escape the attack unlike The Archer Demon.

Ones again, the Beam Attack went through the village and met the ravine from the attack before, creating an X shaped ravine in the village.

"W-Why? Why did I do that? He doesn't have a Nichirin blade. Why am I so worried about him?" Mukago tried to understand the feelings she had at that moment, but couldn't think about it for long before a sword came to her throat.

Mukago POV

(Klin-klong)

The swords between The Lower Moon and The Hashira met. Once again, the dangerous dance of swords had begun, but the Lower Moon couldn't let it go on much longer.

Damn! I'm almost out of blood, if I don't get any soon, I'm going to die. But Rengoku is in the way. He definitely earns the title of Hashira, and his swordsmanship is on the same level as me. I think the only reason I haven't lost yet is that he's not as used to fighting other swordsmen as demons. And then there's Izou. He's not as strong as Rengoku, but his sword technique removes the gap. If I didn't know any better, he doesn't use their breathing technique. Wait, where did he go?

The Demon began to focus less on her opponent and more on her surroundings. All it took was a sneak attack in the right place and this fight would be over. And she felt it, an electrifying sensation on her neck. She jumped out of the way when it looked like she was going to attack, a blade hit her on the shoulder. It was Izou's broken but still working sword.

Izou and Rengoku almost crashed into each other but quickly jumped out of the way and created a space between the three swordsmen. They looked at each other for a few seconds, and as if it were an invisible signal, they began to run towards each other and swing their swords.

" First Form: Unknowing Fire"

Rengoku came first and Mukago had to block the attack. Izou then came from the side and tried to stab her with his broken sword, but because the sword missed a few centimeters, it was enough for Mukago to kick him away. But it distracted her long enough for Rengoku to change form to Third Form: Blazing Universe. That went through her defenses and went down on her head, splitting her helmet mask in two. The two mask pieces fell down on the ground and showed that Rengoku had managed to carve out Mukago's eye, which regenerate not as fast as it should.

To hell with this! I can't survive this! I have to stop this now!

The bloodlust around Mukago increased again tenfold and it was as if the wind itself was trying to escape from the Lower Moon. "I'm going to end this now!" The demon raised the Muramasa up in the air.

Rengoku, who was prepared for something like this to happen, quickly traveled towards Mukago with a First Form: Unknowing Fire to cut off her head. But that's not what happened. Instead of the Beam Attack that Rengoku expected, she swung the sword into an ark. The wind from the attack raised the small gravel rocked from the ground into the air at a deadly speed. Rengoku was too close to dodge and could only prepare for the attack as best he could.

The stones hit Rengoku like a shotgun blast, but it was mostly focused on the legs. With a hundred of small holes in his legs in the middle of his attack, Rengoku could only roll with the speed and tried to dodge all incoming attacks, just as Mukago had planned. With a swing of her sword, Mukago tried to take away one of the toughest opponents she has ever faced. But before the sword could meet flesh, she saw one of the second toughest opponents she had ever faced, Izou. Izou aim at her hand, it was obvious that he was going to cut off both hands in an attack. Losing a hand is nothing for a demon, but losing a Muramasa and with Mukago weaker regeneration, she couldn't afford to take the attack and canceled the swing against Rengoku.

Rengoku finished rolling and went up his feet with a swing of his sword that forced Mukago to jump out of the way if she didn't want to lose her feet. The sword passed over the ground with a speed to create a cloud of dust. It only covered the human for a second, but it was enough for Mukago to think about the situation.

Damn, it didn't do anything! He is still alive. It's just like Lord Muzan said, my greatest weakness is my strength.

In a forest many years ago. Tsurugi Mukago had quickly become the Lower Moon Rank Four, and was now searching for the title of Lower Moon Rank One. Mukago had become the demon who had quickly sped up the Ranks and had spent a lot of time with Lord Muzan. But she didn't know that that night would be the last he would see him.

Mukago had challenged Lower Moon Rank One, Enmu for the title. Lord Muzan stood some distance away from the Samurai and the pale well-dressed man. A short distance away behind Mukago stood Yashin and Yano, silently looking at their master.

"Now, when I give the signal, the match begins. When I say it's finished, it is finished. And the one I say is the Lower Moon One is the Lower Moon One," said Muzan, holding up his hand. After a while, he lowered his hand and Mukago drew his sword.

"Go to sleep".

That was the only thing that happened during the match. After The Lower Moon Rank One said the words, Mukago fell on the ground, the sword halfway out of the case. The two Demon brothers looked at their master, and little sister in surprise, but did nothing. Muzan, on the other hand, sighed and turned to face The Lower Moon Rank One.

"Will he figure it out soon?"

Enmu turned and went down on his knees to answer his Lord's question. "No, Lord Muzan, she accepted the dream without hesitation. Just like the others who did the same, she won't wake up without help."

"I see... Enmu you are the winner. You can let him wake up now."

"But Lord Muzan, I haven't played with her yet."

The veins of Muzan became visible, and he said in a savoury voice. "Enmu. Are you going against my orders?"

Instead of showing fear, the demon's cheeks became red, and he said, "Of course not Lord Muzan" and walked away.

After a few seconds, the Samurai began to wake up and got up from the ground. "What, what happened?"

"You lost."

"What?" Mukago turned to his lord for an answer, but got a look that stared into his soul.

"You didn't stand a chance against him. From the day you became a demon, you've exceeded my expectations. But today you just met it."

"My Lord, I don't understand."

"You have Plateau. Kokushibo also said your weakness, and I can only agree. You only have power."

Mukago looked at his lord in surprise, unsure of what he meant." Excuse me if I disappointed you, but isn't power what you're looking for in a Moon?"

"Yes, but you only have physical strength, while Enmu has strength in his Blood Demon Arts. When it comes to destructive power, you are the one who ranks highest in The Lower Moons. However, everyone in The Upper Ranks could easily defeat you. You don't have the power or ability to get higher. I will contact you when I have an order." And with those words, Muzan began to walk away.

Mukago wanted to go after him, to shout out for his lord. But he knew it would only make him angry. For Tsurugi Mukago had disappointed his Lord.

Yes, against Blood Demon Arts like his and opponents who can survive my attacks, I have almost no chance of winning. My Blood Demon Arts takes too much blood and leaves me weak; my weakness is my own strength.

Mukago couldn't think any more about it after Rengoku and Izou came out of the dust cloud. With swords behind them, they run towards the Lower Moon from both sides. Mukago decided to attack Rengoku first. Not only was he slower from the wounds to the legs but was the only one with a weapon that could kill her. With a speed that only Demons and Demon Slayers can have, Mukago rushed towards Rengoku with an attack that would decapitate the Hashira. Rengoku swings his sword back to meet the attack and Mukago cut through Rengoku's sword... Wait what?

Mukago had cross blades against the Hashira over a hundred times that night and she knew that the sword was heavier than that. She looked at the pieces of the sword that were in the air that hadn't had time to fall to the ground yet. It wasn't the black and red sword that Rengoku had used, it was an ordinary sword. But it was no ordinary sword, it belonged to Izou.

With panic in her eyes, Mukago turned to where she thought Izou was. Just a few yards away was Izou, a sword behind him as if he was preparing for an attack, but Mukago was outside the sword could reach. Before she could figure out what he was going to do, she saw it.

Reduced Earth

A few seconds earlier.

Rengoku finished rolling and went up with a swing of his sword that forced The Lower Moon to jump out of the way if she didn't want to lose her feet. The sword passed over the ground with a speed to create a cloud of dust. It will only cover them for a second, but it was enough for his plan.

Rengoku held his arm in front of Izou to stop him. Izou stared back with a murderous look until he saw what he did next. Rengoku held out his sword with one hand, while he pointed with his other hand at Izou's sword. A smile was created on his face, and he held out his sword in return.

They Swapped Their Swords

After the change was complete, they jumped out of the dust clouds towards The Lower Moon. A loose plan in these minds.

Back to the present time.

With an unnatural speed, he came towards The Lower Moon and the sword smacked into her neck. Metal meeting bones and a burning pain began to spread in her neck. Although Izou is stronger than a regular person, he doesn't have the strength to go through the neck of a Lower Moon who seems to have a tougher neck bone than a regular Demon.

Rengoku, who saw the problem, quickly came up with a solution. He spread back the little remaining sword in his hand and took a deep breath. "Third Form: Blazing Universe!" The sword instead of going towards Mukago's neck, instead went towards his own sword. Sword meets sword and the power of the Blazing Universe is transferred to Izou's attack.

With The Hashira and Assassin giving it all in this attack, it managed to create enough force to go through the neck and decapitate Mukago, thus ending the story of the Lower Moon Rank Four, The Demon Samurai Tsurugi Mukago.

Well, it looks like we ended up with an exciting end to the fight. If you hadn't figured it out, this one is the end of the arc. There will probably only be one more chapter before I go back to Quirk x Hunter.

BTW, what did you think of Tsurugi Mukago. Was it a good OC, a bad one? What's there something I did wrong in the Lore? Tell me please.

And, to end about this character. Here are her stats. Remember that compare with a Servent.

Namn: Tsurugi Mukago

Origin: History (From Manslayers to Demon Slayer)

Region: Japan

Alignment: Lawful-Evil

Gender: Female

Strength: C

Endurance D

Agility C+

Mana E

Luck B

NP D

Skills

Magic Resistance: E

Riding: A

Mana Burst (Wind): B

Eye of the Mind (False): C

Oni-kind Demon (Lower Moon): D

A Skill with represent the connection between Muzan and his demons. The more blood of Muzan the demon has, the higher the skills rank. This skill is also a mixed Skill of Natural Demon, Monstrous Strength and Blood Demon Art, but is seen as weaker than the normal Oni-kind Demon by Izou. But more troublesome thanks to the Blood Demon Art with grant one or more possible powers.

Noble Phantasm/ Blood Demon Art

Demonic Blade Rore: D

Anti-Unit

A technique made with the Muramasa her father's sword. Inspired by Upper Rank One Kokushibo with she met one time. The technique uses a massive amount of energy to turn the air she swings towards to plasma for a powerful explosion. When it coms to power it is as strong as a B to A rank Mana Burst. In fate it is a week Noble Phantasm, but in Demon Slayer: Kimetsu no Yaiba it is a strong attack.

Hayate. Demonic Horse who rides the wind: C

Anti-Unit

A Horse who was a real horse until Mukago one night tried to feed it her blood. Instead of becoming a demon as she thought, it meld into her and become a Blood Demon Art. And in a attempt to strengthen the horse he learn a Blood Demon Art similar to Reduced Earth.

It was Hayate who med it so hard for the Demon Slayer Corps to track her down, different from Reduced Earth he can run for miles without stopping with three demons on his back at that. With Hayate, Mukago can travel from one side of Japan to the other under one week.