Normal POV
"Wait, what?" Yuji asked completely confused and hesitant while Nanami wrapped his necktie around his left hand before blue-green lines reached down reinforcing said limb and cloth.
"You heard me Yuji for the next hour were going to be sparring and in that time, I want you to simply...adapt," Nanami finished settling himself into a boxer stance.
"Adapt," Yuji repeated slowly, "to what exactly?" but is given no time to follow up with his questions.
Nanami had moved.
He crossed the garden in three steps and the first strike came right at Yuji's face.
A gasp leaves his lips as he barely manages to side-step out of the way. Only for Nanami to follow up with an uppercut that forced Yuji to stumble back.
'How will you respond when you don't have time to think?'
Yuji's body answered before his brain did.
Taking a pose similar to Nanami, he responded with a forward punch that Nanami leaned away from leaving Yuji exposed for a hit.
"A decent attempt at copying me but-" Nanami goes in to punch him but Yuji grins as he ducks around his fist and gets close to his stomach due to his small stature.
"DIVERGENT FIST!" blue energy explodes out from Yuji's fist as he lands a solid blow.
The impact cracked through the air like a thunderclap which sent dust spiraling up from the garden stones.
Nanami slid back.
His shoes carved two clean lines through the dirt before he dug his heel in and stopped, tie-wrapped hand braced against the ground. A faint ripple of reinforcement shimmered across his torso where Yuji had struck.
'If I hadn't reinforced myself in time that blow would have for sure broken some bones,' Nanami warily thought to himself.
The lag of Divergent Fist took into effect slamming a hard invisible punch right in the same spot. But thankfully his reinforcement still allowed him to tank the attack.
It would take more than just a couple of punches to put a former enforcer like Nanami down, he wasn't even really going all out.
Yuji was still a kid after all, even if he was a bit more monstrous than normal ones.
"Not bad," Nanami complimented standing up to his full height.
"Oh shit are you alright Nanamin-" Yuji's comment was cut off when the blond haired man vanished from his line of sight.
A pressure slammed into Yuji's side before his eyes could track the movement. His ribs lit up with a dull pain as he was launched sideways, tumbling across the grass until he dug his palms in and skidded to a stop.
"Wha-?!"
"To slow!"
Yuji barely had time to cross his arms before Nanami's appeared in front of him with his reinforced fist hammered down. The ground cratered beneath Yuji's feet as he blocked, legs shaking from the force.
"Then I'll go faster!" Yuji exclaimed.
He twisted, dropping low, sweeping his leg out. Nanami hopped over it effortlessly. Yuji however was already moving, springing upward with a rising punch empowered with mana.
Nanami caught Yuji's wrist mid‑air "not enough. Where I to be an actual enemy your hand would have been chopped meat."
Yuji's eyes widened but then he grew a mischievous grin that made Nanami raise an eyebrow "true," he said, "but it looks like my idea was right."
The second impact of Divergent Fist exploded from Yuji's trapped arm, blasting Nanami point‑blank in the chest. The force ripped Nanami's grip loose and sent him sliding back again, this time with a faint grunt.
"I stopped you from landing the blow though so how?" Nanami questioned.
Yuji landed, panting, hands trembling with leftover mana "I just figured the lag effect from Divergent Fist would still pick up following the trail of kinetic energy of my first strike which you stopped. From there it was only a matter of a second for it to explode out," he explained.
Nanami straightened his tie-wrapped hand, brushing dust from his shirt "I see then in that case I'll have to not hold back so much. Seven percent is where I'll stay at no more, no less," he replied.
Then he disappeared again.
A shockwave burst outward from where he'd been standing, grass flattening in a perfect circle. Yuji barely had time to tense before Nanami reappeared in front of him, fist ready.
The punch hit Yuji's crossed arms like a sledgehammer. The world blurred as he was blasted backward, skidding across the dirt hard enough to tear trenches behind his heels. His arms were littered with cuts while his bones vibrated from the impact.
"Gah! That's seven percent?!" he exclaimed as the cuts began to rapidly heal. Something Nanami kept notice of as he went for his next attack.
Yuji braced then dropped flat as Nanami's punch sliced overhead, the air splitting with a loud crack. The shockwave tore a clean line through the hedge behind him.
Yuji rolled, sprang up, and lunged forward with a mana‑coated fist.
Nanami sidestepped.
Yuji's punch hit the ground instead causing a large BOOM!
Dirt erupted upward in a geyser.
Nanami's voice came from behind him "behind you."
Yuji spun around, swinging wide. Nanami caught his wrist again and twisted, redirecting Yuji's momentum and slamming him into the ground.
Yuji coughed, dust exploding around him.
"Damn Nanamin, you're built like a tank!"
"Incorrect," Nanami dully replied, stepping forward, "I am simply just waste little energy in how I fight that's all."
He then stomped down.
Yuji rolled away just in time, Nanami's heel cracking the stone beneath them. Yuji scrambled to his feet, adrenaline spiking.
"Okay-okay! Think, Yuji, think!"
Nanami blurred again.
Yuji did not in fact think at all actually.
Instead, his eyes suddenly shifted to a red color making the world appear slower and sharp in detail.
Just like when he had first done so with one of the kid's he could not save, Yuji could see a colored orb where Nanami's heart was located.
This he would later learn was where the soul was located and what it looked like. But for now he would take advantage of his sight to get a read on when Nanami would attack.
In this very moment...he had begun the process of adapting.
'His mystic eyes just activated,' Nanami warily thought to himself.
During these next few minutes nothing really happened with Yuji still struggling.
Then just as Nanami went for another hit Yuji's body reacted instantly.
He stepped off-line instead of back, just like Nanami had been doing to him. The fist that would've shattered his guard instead brushed past his cheek.
A sharp whoosh sung through the air.
Nanami's eyes narrowed slightly 'he avoided it...before I completed the motion.'
Yuji didn't stop.
He pivoted, still sloppy for sure but managed to drive his fist toward Nanami's ribs.
Nanami in response twisted, catching Yuji's wrist. The kid didn't freeze though instead he rotated with the grip.
'This kid in just a short amount of time has already begun learning and implementing my own moves. What monstrous talen!' he mentally exclaimed.
Yuji's shoulder dipped, his stance tightened bleeding directly from Nanami's own movements.
"I can understand it better!"
'Wait...don't tell me I accidentally made the kid into a battle maniac?' the blond detective inwardly remarked to himself.
Nanami struck again with an even slightly faster speed.
Yuji reacted.
He slipped one hit, blocked another, and redirected a third. Each movement, rough, and inefficient but without a shadow of a doubt evolving.
Using his short form to his advantage Yuji lunged again "DIVERGENT FIST!" he roared.
CRACK!!
Nanami blocked, but his stance shifted back half a step.
Yuji pressed forward again, breath heavier now as he began mirroring more of Nanami's previous footwork. Stepping in diagonals instead of straight lines. His guard rose higher and elbows tucked in closer.
Nanami leapt back away "...half an hour," he murmured.
Yuji blinked "huh?"
Nanami adjusted his stance again "in less than thirty minutes you actually managed to reconstruct some of my combat style to suit it for your own needs."
Yuji scratched his cheek, grinning "it's not as easy as you make it out to be Nanamin. I mean I am still getting my butt kicked by you."
Out loud, he said nothing but he did give a slight smirk.
Then he dashed forward again.
Faster than before.
Yuji's eyes widen as he struggled to see where Nanami would appear.
'Step, move, and guard,' Yuji mentally recited managing a block just in time.
The ground cracked slightly beneath his feet, but he held strong.
Nanami's eyes flickered 'his durability is also incredible given enough time the kid may even reach a tank level higher then me."
Yuji out of no where began laughing with delight.
"THIS...THIS IS SO AWESOME!"
His mana flared widely but something was wrong with the color. Instead of being a blue color it had darkened into a deep violent, pulsating red.
Nanami's expression grew slightly grave.
The kid hadn't even noticed it yet or maybe just didn't care.
Yuji's let out a widened smile that looked sinister.
Black markings began creeping across his wrists, crawling upward like ink bleeding through skin. Thin lines traced along his cheekbones, curling at the edges of his face.
His eyes gained a tint of bloodlust while his pink hair slicked back slightly
"Let's go again, Nanamin!"
Yuji rushed forward with a Divergent Fist.
Nanami blocked but the impact felt different.
THUD!! The secondary lag hit came out much stronger and heavier. The reinforcement Nanami had casted almost broke from the sheer abnormal strength.
'His mana it's...different now and this feeling it's exactly the same as back then when I saw his core,' he thought with a bead of sweat.
Yuji pressed on relentlessly now, his movements aggressive, and impeccably faster. His style of combat still carried Nanami's structure but it was now more barbaric.
Punch.
Elbow.
Step-in.
Nanami parried, redirected, and countered them all in time but his mind was no longer focused solely on the fight.
'I need to put an end to this quickly..'
Yuji rushed with a punch and Nanami timed his next move just in time.
His hand shot out landing a perfectly controlled strike to the side of Yuji's neck.
"Gah!" the kid gasped his body freezing as the red mana around him flickered before shattering like glass.
The black markings on his body faded away instantly.
His eyes rolled up slightly then his body went limp.
Nanami caught him just before he hit the ground.
He looked down at Yuji's unconscious form with a rather tense expression "...so he really did turn into a battle maniac. Although," he trailed off.
His gaze lingered just a bit longer on Yuji's now-normal face.
"...That presence...I should definitely see what my contacts managed to find out about his family."
Nanami turned back carrying Yuji back into the house.
-end of chapter eleven-
So just to explain the more excited Yuji get's in battle and the more he taps into his mana the more of Sukuna's traits begins to blend and synchronize with him. Were also not going to see Dismantle or Cleave appear until way later when Yuji meets up with Rin for the first time.
His mystic eyes appear as a red color.
As usual positive comments and stones are a great boost to my motivation. I've got a discord linked in the synopsis so check it out if interested…or don't.