Muzan charged with both whips extending in crossing patterns at full length.
The weapons crashed into Sasuke's staff with enough force to splinter the wood completely. Fragments scattered across the ground and Sasuke stumbled back with empty hands.
"Menma! The staff!"
Smoke erupted beside him. When it cleared a black metal rod sat in Sasuke's hands. He spun it once and charged straight back in.
They already knew about the hearts. Every exchange from the first second was aimed at the chest with that single objective in mind.
Kaze moved wide and formed seals. "Wind Release: Drilling Air Bullet!"
The spinning sphere forced Muzan to raise both whips to deflect it. Sasuke drove the extending staff into the opening and punched through Muzan's chest. The staff hit bone and cracked it but found nothing vital. Muzan healed and pushed forward.
Sasuke retracted and drove it through again from a lower angle. Flesh and muscle gave way but the heart wasn't there either.
Kaze shifted position and sent another technique to force Muzan's movement. "Wind Release: Vacuum Wave!"
The cutting current opened Muzan's side. Sasuke immediately angled the staff through the new wound and drove it deep. He felt the tip scrape against something and pushed harder.
Nothing. Wrong location.
They kept at it. Sasuke drove the staff through from above, from the side, from below, probing through flesh and bone while Kaze used wind techniques to keep Muzan off balance and unable to protect himself properly. Muzan healed each wound as fast as it opened and countered with his whips, forcing both men to keep moving to avoid the blades.
The exchange went on for two full minutes and the clearing showed the damage of it. Trees were split and scarred from deflected strikes. The ground was torn open in long furrows. Blood soaked into the ash from wounds on all three of them.
Then Sasuke drove the staff through the left side of Muzan's chest at a downward angle and felt something give way differently than muscle and bone.
A heart was destroyed.
The loss hit Muzan like a physical blow from the inside. His legs buckled and he dropped to one knee. His vision grayed and his hearing cut out for two full seconds before the remaining organs compensated and forced his body back into function.
Six hearts left.
Sasuke pulled the staff free and came in immediately before Muzan could recover. He drove it through the same general area from a different angle and found only muscle. He retracted and tried again. Muscle again.
Kaze pressed from the other side. "Wind Release: Vacuum Serial Waves!"
The cutting currents drove into the open wounds and shredded through tissue and bone. The damage was catastrophic. Muzan's regeneration slowed to almost nothing and blood poured from his chest in thick streams. He dropped to both knees and coughed blood into the ash.
He had to break the pattern before they found another heart.
He lunged forward with everything he had left and sent both whips out wide to force Kaze and Sasuke to separate. Sasuke jumped back and blocked with the staff. Kaze moved left and raised his fan to deflect the second whip.
Muzan redirected his right whip mid-swing and wrapped it around Kaze's leg before the clan head could fully clear the attack.
He pulled hard.
Kaze's feet went out from under him and his war fan hit the ground three meters away.
Kaze hit the dirt and rolled immediately, trying to create distance and recover his weapon. Muzan's left whip came down and pinned his arm before he could reach the fan.
Kaze looked up at the blade hovering above his chest. His expression didn't change. He was calm and completely without fear and his hands were already moving through seals despite the whip holding his arm down.
"Wind Release: Vacuum—"
Muzan drove the blade through his chest.
The wound was fatal and both of them knew it. Blood poured from Kaze's mouth in a continuous stream. But his lips kept moving and his hands kept forming the seal and his eyes stayed open and focused.
The technique completed on his last breath.
"—Great Sphere!"
The compressed air launched point-blank into Muzan's torso with nothing between them. It burrowed through muscle and bone without slowing and found its target. Another heart was destroyed from the inside.
Muzan's vision went white. The ground came up and he couldn't stop it. He lay on his back in the ash and couldn't hear anything and couldn't feel his legs.
He let the whip go. Kaze's body settled slowly to the ground.
"KAZE!"
Sasuke's voice cut through the white in Muzan's hearing. He turned his head and saw Sasuke on his knees beside Kaze's body with both hands gripping the man's armor. Sasuke's face was open in a way it hadn't been at any point during the fight. The grief on it was total and unguarded.
He stayed there for several seconds. Then he looked up at Muzan.
Five hearts remained. Muzan's regeneration was barely functional. He pushed himself to his feet and the movement was slow and deliberate in a way it had never been before.
Sasuke's chakra erupted outward in a visible wave. The ground beneath his feet cracked in a web pattern and the trees nearby bent away from the pressure. His grief had compressed itself into something cold and singular and focused entirely on Muzan.
He formed seals with shaking hands. "Fire Release: Dragon Flame Song Jutsu!"
Four dragons of blue-white flame erupted from his mouth simultaneously. Each one was forty feet long and converged from every direction. The heat vaporized stone before the fire arrived and the ground turned to molten glass.
The dragons hit from all sides at once.
When the flames cleared, almost nothing remained of Muzan. A charred skeleton sat partially sunk into cooling glass. One arm was completely gone. His legs ended at the knees.
Sasuke leaned on the black staff with his chakra completely empty. Every wound across his body bled freely. He stared at the wreckage and his breathing was the only sound in the clearing.
One of the charred ribs shifted.
Deep inside the wreckage, protected by what remained of the ribcage, hearts were still beating. Weak and irregular but present.
Flesh grew outward from the bones one layer at a time. The process was slow and painful and visible and took a full minute. But at the end of it Muzan stood up.
Sasuke watched without speaking. The staff kept him upright. His knuckles were white around it.
"Why won't you die?" he finally asked, his voice low and raw.
"Because I can't," Muzan said.
Sasuke looked at Kaze's body one more time. Then he turned back and lifted the black staff properly in both hands and straightened his posture despite everything it cost him.
"Menma," he said quietly. "One last time."
The staff pulsed with weak chakra. "Together until the end," the monkey answered.
Sasuke charged without techniques and without tricks. Just a warrior and his weapon moving toward something that had already killed his closest friend and couldn't be killed in return.
He came in low and drove the staff forward on an extending thrust. Muzan tried to move but his body was too slow.
The staff punched through his sternum. By chance it found one of the remaining hearts and crushed it.
Four hearts left.
Muzan caught the embedded staff with his left hand before Sasuke could pull it free. His right arm changed. Red tissue erupted from the forearm and the whip formed, shorter than before but the blade at the tip was intact.
Sasuke released the staff and drew his last kunai.
The whip wrapped around his torso. The spines drove through what remained of his armor and through his flesh and between his ribs.
Sasuke gasped and blood came from his mouth. But he lunged forward along the whip and closed the remaining distance with the kunai coming up at Muzan's throat.
Muzan caught his wrist. The bones cracked under the grip.
The kunai fell.
They stood face to face with inches between them. Sasuke's blood ran down the whip and dripped onto the ash.
"You fought well," Muzan said.
Sasuke smiled with blood between his teeth. "Not well enough." His eyes moved to where Kaze had fallen. "I'm sorry, my friend. I couldn't finish it."
The whip contracted. The spines drove deeper and found his heart.
Sasuke's body went still. The defiance in his eyes faded out completely and left them dark.
Muzan released the whip and Sasuke fell beside Kaze. Their blood spread together across the ash.
The black staff vanished in a curl of smoke.
Silence returned to the clearing.
Muzan turned and walked to where Amanai was propped against the broken tree trunk. The man's Sharingan spun weakly with the tomoe barely visible.
"What are you?" Amanai whispered.
Muzan knelt beside him. "Something I don't fully understand yet."
Amanai's hand found Muzan's arm. His grip was almost nothing. "I don't know if you were ever truly Uchiha." He pulled a breath that sounded wet and shallow. "But to us, you will always be Uchiha Muzan."
His hand fell. His breathing stopped. The red faded from his eyes and left them dark.
Muzan closed them and stood.
He looked at the clearing for one moment. Bodies and dying fires and the smell of blood and ash.
Then he walked into the burning forest and didn't look back.