A misty figure shot out from the shadows of a broken wall behind Akaza's flank without warning.
But Akaza had already sensed a third party joining the fight. He immediately activated his Destructive Kill: Compass Needle. A dazzling snowflake array spread instantly beneath his feet.
In the instant Tokito Muichiro was about to make contact with Akaza's skin, Akaza twisted his body in a wildly exaggerated motion and swept his right fist toward Muichiro.
The violent wind kicked up by Akaza's punch instantly dispersed the lingering haze.
With a deafening crash, Akaza sent Muichiro flying with a single punch. The terrifying force nearly tore the Nichirin blade from his hands.
His entire body, like a kite with snapped strings, slammed viciously into a nearby courtyard wall. The impact blasted a hole straight through it, sending clouds of dust billowing.
Blood sprayed from his mouth and nose. The searing pain in his chest confirmed that his ribs had been broken by that defensive blow.
Muichiro understood from that single strike that the Upper Moon Three before him was a terror unlike any demon he had ever cut down.
Akaza ignored the slayer he had just sent flying. His expression cold, he turned toward Gyomei rushing at him.
He noticed the strange markings on Gyomei's arms. He could also sense that with the appearance of this marking, Gyomei's fighting spirit had suddenly surged.
Even so, Akaza did not believe the man could defeat him. Still, he found it a pity. This was the human with the strongest fighting spirit he had ever seen. Sukuna did not fall within Akaza's definition of human.
If this were before, Akaza would have tried to persuade this man to become a demon, or even forcibly convert him. He had the right to do so.
But unfortunately, not anymore. Now, Akaza needed to kill everyone here.
"Destructive Kill: Annihilation Type!"
Akaza roared and swung his fists rapidly. The terrifying shockwaves, carrying the force to tear Gyomei apart, surged toward him.
Even with Transparent World, even anticipating the strikes by reading Akaza's muscle movements, Gyomei could not avoid taking several of those shockwaves head-on.
Even with the Mark's enhancement, Gyomei's body could not match Upper Moon Three Akaza.
The sound of impacts rang out again and again. Each one drew more blood from Gyomei's body.
Sukuna could see that after reactivating his Mark, without Sukuna's Reverse Cursed Technique to heal him, even if Gyomei somehow survived this battle, his life would soon run out.
Sukuna had no intention of intervening this time. This had nothing to do with him.
If anything, Gyomei's death might provoke more potential from the other Demon Slayer swordsmen. People like them always responded that way.
Sukuna's gaze shifted to Muichiro. He was curious to see if this severely wounded boy, witnessing his comrade being battered like this, would surprise him.
"Himejima-san!"
Muichiro struggled to rise from the rubble. Watching blood spray from Gyomei's body again and again, a suffocating mix of fear and helplessness seized him.
He knew Gyomei was stronger than him. But even so, if this continued, Gyomei would only die.
In that moment, Muichiro's life flashed before his eyes. He remembered that day again, when a demon attacked him and his brother. His brother's dying words echoed in his ears.
"I... I understand now... Muichiro's 'mu'... it's the 'mu' of 'mugen'... infinity."
"You are the chosen one... who can draw upon infinite strength for the sake of others..."
In that instant, Muichiro's body began to change. A boiling heat erupted from his heart and swept through his entire being.
He could feel the fire in his body. On his cheek, a deep red, cloud-like pattern suddenly emerged.
"Oh? So you've awakened your Mark too, have you?"
Sukuna had witnessed the entire process of Muichiro's Mark manifestation. Immediately, he began analyzing it.
This case was slightly different from the awakenings of Rengoku Kyojiro and Gyomei Himejima. Rengoku and Gyomei had awakened their Marks during combat against Sukuna himself. Muichiro, strictly speaking, had awakened his while preparing to attack Akaza.
"Mist Breathing...!"
Muichiro was about to attack Akaza when Sukuna grabbed him by the neck and lifted him up. Sukuna carefully observed the changes in Muichiro's body.
The first thing Sukuna noticed was the rapid, high-frequency pulse of the blood vessels in Muichiro's neck. The boy's heart was racing.
Could the Mark's awakening be related to this?
Was the heightened heart rate caused by the pressure of combat and danger, which in turn triggered the Mark?
But that could only be one factor, not the whole answer.
Increasing heart rate was far too easy to achieve.
Sukuna quickly dismissed that idea. He considered whether the increased heart rate might instead be a secondary effect of another cause.
He worked backward, considering what could accelerate the heart. Exercise, intense emotional shifts, dehydration, anemia, blood loss, fever.
Exercise, emotional shifts, and blood conditions could probably be ruled out. These had occurred countless times in battles between slayers and demons, well before any Mark awakening.
but why was this brat's body temperature so high?
Could it be that the racing heart was actually a mechanism to accelerate the body's metabolism?
Elevated body temperature, rapid heartbeat, burning through one's lifespan. Was that the reason?
"Muichiro had no idea what was happening. He stared wide-eyed at the man who had abruptly inserted himself into the battle."
Had Sukuna been on Upper Moon Three's side from the very beginning?
But if Sukuna joined the fight... how could they possibly win?
Against Upper Moon Three, Muichiro could still muster the will to fight to the death. But Sukuna was the one who could snuff out even that last shred of hope.
Akaza also looked toward them. He had sensed Muichiro's fighting spirit suddenly spike, just like Gyomei's. But when he turned, he saw Sukuna holding the boy by the neck with one hand.
Just as the battle ground to a halt due to Sukuna's intervention, Sukuna released Muichiro and spoke with a smile.
"You may continue."
"...?"