Based on that description alone, one might think Aka isn't all that remarkable.
After all, it's only about changing the upper limits of talent, not adding bloodlines or anything exotic... While such an ability is extraordinary, in a Shinobi World that places even greater value on bloodline... even a genius like Kakashi ultimately needed Obito's eyes to be relevant in the final battles.
If you think that, you probably haven't deeply considered the deeper implications of altering talent ceilings.
If Aka has life force and regenerative capacity like Naruto's, then her Chakra wouldn't be less than his.
Because Chakra is energy refined from physical and mental cells. The stronger those cells, the more Chakra can be refined.
Building on that, if Aka also possesses mental strength, taken from others, that far surpasses Naruto's, then her Chakra would exceed Naruto's.
Then, with this massive Chakra Reserves as a base, if Aka also has monstrous physical strength and Chakra Control like Tsunade's... then she could achieve instant healing without the Strength of a Hundred Seal, much like the First Hokage.
Then, building on that, if she also has all five Chakra Natures like the Third Hokage and Kakashi's talent for learning Ninjutsu at a glance... she becomes a living artillery piece.
Then, building on that, if she also has Minato's inhuman neural reflexes and Sasori's ability to split his focus a hundred ways... she becomes a precision bombardment platform, hitting exactly where she aims.
Then, building on that... cough.
Alright, Ryuji's imagination is limited. Without precise calculation, he doesn't know all the possible effects. The combinations above are just what he can roughly conceive.
If you kept layering infinitely, how strong Aka could become is something probably even she doesn't know.
However,
Upper limit is one thing; actual power is another.
Naruto's Chakra wasn't fixed from birth. Sasuke couldn't awaken the Mangekyo Sharingan the moment he opened his eyes.
Reaching the peak of one's potential still requires training and growth.
But talents like Minato's neural reflexes, Sasori's multi-tasking, Hiruzen's five Chakra Natures, Kakashi's learning ability... these are innate. They were present from the start.
Therefore, Aka isn't as omnipotent as one might imagine, but she is still incredibly, incredibly powerful.
Perhaps going from a 'game-breaking' level to a 'system-breaking' one.
However.
All of this is based on Aka's own capabilities... When fighting using Kuro's borrowed body, the only advantages she can leverage are her mental and conscious talents.
The reason for Ryuji's confidence in Aka's victory stems from an enemy he once faced.
Back then, he was still a Chunin.
During a merchant caravan escort mission, he encountered an opponent whose calculation ability was like a machine's. This person could calculate the number, trajectory, and method of attacks the instant puppet mechanisms activated... a veritable human computer.
Ryuji only won back then by using attacks that, even if calculated, couldn't be dodged or neutralized.
As he hadn't considered cloning technology at the time, he didn't preserve the corpse.
But the memory of this person stayed with him.
When Aka was born, she directly possessed that computer-like calculation ability.
With such computational power, coupled with understanding each other's personalities and abilities, Aka simply could not make a mistake.
In the end, the battle's outcome matched his expectations.
...
"It's... my loss."
Looking sideways at the hand blade embedded in the wall beside her head, Tsunade conceded with a grim expression.
Tsunade's tactics had been simple: rely on vast combat experience and physical qualities far superior to her opponent's to defend stubbornly, aiming to exhaust him with her immense stamina and Chakra.
But the flaw was significant.
Once a lapse in her defense occurred, her only recourse was to use brute force to shatter the terrain and reset the situation.
This method had a large recovery period. She couldn't act immediately after such an attack.
After forcing one such lapse from Tsunade, 'Kuro' used a clone to bait her terrain-shattering counter. His real body followed up in the precise instant after her recovery, ending the match.
If the earlier hand blade piercing her abdomen missed vital spots due to positioning, this time it was genuine restraint. A slight shift would have severed her artery.
Tsunade wasn't a sore loser. Though deeply displeased, she conceded openly.
Her words caused an uproar throughout the stadium.
The Sunagakure's Shinobi celebrated with joy. The Konoha's Shinobi reacted with disbelief or sighs.
Tsunade losing... Before the match, they hadn't even considered it.
Her opponent was a nobody. Tsunade was one of the legendary Sannin, acknowledged by the Demigod himself on the battlefield years ago, renowned and powerful.
The result... sigh.
"This duel's winner is... Kuro of Sunagakure!"
As Minato announced the result, the cheers grew louder. Even the Konoha's side began to applaud.
Though regretful, the opponent had genuinely defeated Tsunade with skill, earning their respect.
'Kuro' withdrew his left hand and looked toward Ryuji in the stands, an affectionate smile appearing. "Master, I've completed your task. Please don't blame me."
Aka transmitted this through the spiritual network, her soul swapping back with Kuro's... Then, Kuro's vision darkened, and he collapsed.
The noise in the stands died instantly. Everyone stared in stunned silence.
Tsunade, after a moment's pause, hurriedly checked him.
After a moment, she sighed in relief. "He's in shock. Get him to the hospital."
"Woo-hoo!!!"
Cheers once again shook the stadium, wave after wave. With just over a hundred people, it sounded like several hundred.
"Suna... truly a force to inspire awe."
Watching the medical staff carry Kuro away, Hiruzen couldn't help but sigh.
Ryuji also let out a breath of relief.
When Aka said not to blame her and then passed out, he thought something had happened to her. Turns out she just broke Kuro's body!
'What's the big deal?!'
'If it's broken, I can just make another one.'
'She made me worry for nothing.'
As everyone reacted, the participants for the second duel entered the arena.
On one side: a young woman with silver hair and silver eyes, striking features, a tall and slender build, wearing form-fitting attire… Gin.
On the other side: a man around 1.7 meters tall, in his early twenties, with stubble on his lips, casually drinking from a bottle… Kohinata Mukai.
"Alcohol?"
Seeing this, Ryuji frowned slightly.
As he had never heard of this character in the original work, he was particularly curious.
But seeing this unkempt appearance and the act of drinking before a duel left him puzzled about this man.
This wasn't a wuxia world. Being unkempt and drunk, without the narrative protection of character design, would only get you killed faster.