"Breath of the Moon, Ninth Form:Waning Moonswaths!"
Kokushibo creates a seemingly endless stream of slashes, capable of cutting down his intended target from a long range. Seeing this, Yozora calmed his nerves as he had a plan to counter this.
"Shigure Soen Ryu, Fourth Form:May Wind, October Rain."
Yozora synchronized with Kokushibo's breathing to evade the Upper Moon's attack at high speeds. Soon Yozora dashed behind Kokushibo and swung his sword. Just as the demon turned around, Yozora's plan was already in motion as his crimson nichirin sword was coated in light blue flames.
"Shigure Soen Ryu, Fifth Form:Early Summer Rain."
Yozora swung his sword with his right hand, but Kokushibo jumped back in hopes of dodging it. However, the first slash was a feint as Yozora dropped his sword into his left hand and slashed Kokushibo across his chest.
"Breath of the Moon, Fifth Form:Moon Spirit Calamitous Eddy!!!!"
Kokushibo makes multiple curved slashes layered over one another, resembling a rising vortex. Numerous chaotic blades originate from these slashes. As Yozora was too close to evade, he felt his body being slashed multiple times. As he gripped his sword, he tried to destroy Kokushibo's attack before it could do more damage.
"Breath of the Moon, Tenth Form:Drilling Slashes - Moon Through Bamboo Leaves!!!!!"
Yozora creates a triple-layered slash twister, capable of mowing down Kokushibo's attack into three clean pieces. As they jumped back, the two swordsmen started breathing heavily. Kokushibo felt nothing but rage consuming his very being when he looked at Yozora. There was only one other person who made him feel like this.
"Brother your dream was to become the strongest samurai in the country, right? I want to be like you as well. I want to become the second strongest samurai in the country."
An unpleasant memory went through Kokushibo's head. The only person that made him feel so inferior....why? Why did Yozora seem to be more and more like him of all people?
"No wonder he's ranked the strongest amongst all the Upper Moons. I can't win this fight if i hesitate or restrain myself. Plus with this battlefield....i have an advantage."
Kokushibo looked at Yozora as he was trying to anticipate what his next move was. However, he was surprised when he saw the boy sheath his nichirin sword and suddenly picked up a random sword from the ground.
As Kokushibo saw this, he noticed that Yozora is starting to get even more serious. When he looked at him, he saw red markings resembling flames appear on his face and neck.
"So he's using the mark. It seems this battle is about to grow even more difficult."
"Inifinite One-Sword Style:Addition Mode!!!!"
Suddenly Yozora was out of Kokushibo's sight. When the Upper Moon looked around for his opponent, a sword was suddenly in his arm. As he turned towards the direction the sword came from, no one was in sight. This process repeated over and over.
After each hit Yozora would let go of a sword to quickly use another to let himself attack from different angles while his Kokushibo is stunned from his previous blow. Usually this would end with leave Kokushibo covered in twelve swords, but due to Yozora's newfound speed and the numerous amounts of swords in the area, Kokushibo was surrounded by thirty swords.
"Infinite One-Sword Style, Multiplication Mode!"
Immediately after using Addition Mode, Yozora unsheathed his black nichirin sword and struck all the swords that surrounded Kokushibo's body, resulting in sixty slashes in just a single moment.
As the demon's body was dismembered, he looked as if he was in awe. Kokushibo had to admit that Yozora's technique was terrifying. As his body was regenerating, he looked at Yozora.
"Those were the same techniques you used on me last time. Is that really the limit of the sword style that you created?"
When Kokushibo said that, Yozora just stared at him as blood was dripping from the wounds Kokushibo gave him earlier. He unsheathed the black nichirin sword and held the blade tightly as he looked around and saw that he was surrounded by a multitude of swords. As Kokushibo held his sword and charged, Yozora said one thing.
"Infinite One-Sword Style:Jumbled Line Up."
Yozora initiates this technique by spinning the nichirin sword in his hand in a circular motion, causing all of the blades in the immediate vicinity to be propelled upwards. By then utilizing the collisions between the swords to keep them aloft, Yozora is able to ensure that he is continually surrounded by a large quantity of blades regardless of his subsequent movements.
"You asked me if i reached the limit of my Infinite One-Sword style. Hate to break it to you, but its the opposite. What you're about to witness is the peak of the sword style that I made."
Yozora jumped in the air with the swords floating around him. Kokushibo soon leaped towards Yozora as he wasn't going to let this fight go his way.
"Breath of the Moon,Fir-"
"Infinite One-Sword Style:Jumbled Line, Sword Fang!"
Using the sword in his hand, Yozora hits the back side of the swords in front him downward which resulted in all three swords slashing down on Kokushibo's body simultaneously.
As they land on the ground, Yozora looked up and saw the swords he used in his Jumbled Line technique falling down. Soon he jumped back and hits the hilts of all the swords with his own nichirin sword to launch them at Kokushibo. Seeing this, the Upper Moon used his own sword to block the majority of the swords.
"Wait.....something's different....what am i seeing? What am i sensing?"
Kokushibo's instincts were yelling at him to turn around. As if his body was moving on its own, Kokushibo suddenly swung his sword behind him. When he looked in that direction, he saw that he blocked a sword strike from Yozora.
"This feeling.......along with the See-Through World and my breath.........i see.....so that is how he evolved my breath of the moon."
When Kokushibo looked at Yozora, he noticed something different. While Yozora's body was see through because he had access to the see through world, he saw something akin to an aura surrounding Yozora's body. As this happened, Yozora's eyes widened as he jumped back.
"He's able to do it too..........Michikatsu........can sense ki!!!"
~Meanwhile~
Muzan is seen in an area all by himself. He sensed that Akaza and Douma were defeated. However, he knew that Kokushibo was still alive to fight against the Demon Slayer Corps.
"I will not lose here. I have survived centuries in order for this moment. I will absorb Nezuko and conquer the su-"
Muzan stopped his sentence as he felt the presence of a demon slowly approaching where the war is taking place. The strength of this presence was immense as Muzan started to sweat nervously.
"What is going on here?"
~With the demon~
"Muzan truly is a fool. He's so busy trying to hunt down a demon who conquered the sun, that he never even stopped to think about if he was being hunted. Rejoice Muzan, for a demon who has conquered your weakness is slowly approaching. However, it is YOU who will be devoured."
As Yhwach walked away from the hideout that Tokinada and himself occupied, he smiled to himself as he made his way to where Muzan and the Demon Slayer Corps were having their battle.
"Your thrown, your power, your goal, i am the person who will take everything from you. Kibutsuji Muzan, the true king of all demons will arrive shortly."
Time left until Yhwach's arrival.......one hour.