"Naruto-kun, you're going too deep… it hurts so much!"
Kisame's screams were relentless, but he dared not move an inch.
Since he had agreed to participate in the experiment, he wouldn't back out now.
"Stop shouting. This kind of injury isn't fatal. Don't use Samehada to recover… bear with it. Let me stab a few more times."
Naruto raised the small knife and slashed Kisame's body several more times.
It had to be said, choosing Kisame as a test subject was the best decision.
Naruto still couldn't guarantee the immediate effects of rapid healing, but Kisame's Samehada could restore his injuries, so there was no fear of the experiment failing.
Kisame's body was soon drenched in blood, riddled with wounds… Although he was not covered with holes, there were at least dozens of injuries.
"That should be enough."
Naruto nodded in satisfaction. He then brought his index and middle fingers together on his right hand, raising them to his forehead in a pose resembling instant teleportation.
Silently activating his rapid healing ability, he extended his right hand and pointed at Kisame from a distance to lock onto his target.
At the next moment, a green aura brimming with vitality appeared beneath Kisame's feet, enveloping his entire body from bottom to top.
Sizzle!
Astonishingly, the damaged areas of Kisame's body began healing at a speed visible to the naked eye.
In less than ten seconds, Kisame's injuries were completely restored without leaving a single scar.
Only the bloodstains on his torn clothes served as evidence of the ordeal he had just endured.
"Kisame, tell me how it feels." Naruto asked eagerly.
"Hmm... It feels great, really comfortable!"
Kisame struggled to find the right words and added, "It was like the sharp pain from the wounds suddenly turned cool and soothing. It's like going from a scorching summer day to a refreshing autumn breeze. It's just really pleasant."
"You're saying that the moment the green aura appeared, the pain stopped?"
Naruto pressed further.
This question was critical. If the pain persisted until the healing was complete, the target would still have to endure a few seconds of agony. But if the pain disappeared instantly, then Rapid Healing would have broader applications.
For example, Naruto could activate Rapid Healing before a battle, even if he wasn't injured yet. So during the fight, he wouldn't feel pain, allowing him to concentrate better on combat.
Moreover, the duration of Rapid Healing was 15 seconds… 5 seconds longer than the 10-second cooldown period. In simple terms, he could reapply the ability repeatedly, ensuring he wouldn't feel pain at any point.
Of course, the most important thing is Kisame's answer.
Kisame recalled, "The moment the green aura appeared, I didn't feel any pain anymore. Also..."
"Also what?" Naruto inquired.
Kisame explained: "Normally, when wounds heal, the lost blood doesn't come back. I was about to use Samehada to replenish my blood, but I felt completely fine… my blood felt full, like it had truly been restored. Honestly, it's as if my body's time was reversed to before I was injured. It didn't even rely on regenerating my cells."
Under normal circumstances, any healing method would rely on the body's cells for regeneration, which had a limit. While reaching that limit was rare, if it happened, the body would be permanently damaged.
For members of the Akatsuki, who frequently undertook dangerous missions, it was common to approach that limit in the long run.
But Rapid Healing provided recovery without cellular strain, which was truly terrifying.
"Excellent feedback. This experiment was a success." Naruto said, nodding in satisfaction.
In Naruto's view, the Rapid Healing ability was not just a practical skill for combat but also an incredibly flashy and impressive one. After all, saving someone was often harder than killing them.
"Alright, I've got other things to handle. Rest early," Naruto said, waving his hand. In a flash of golden light, he disappeared from Kisame's room and reappeared in Itachi's quarters.
Seeing Naruto covered in blood, Itachi asked, "How did the experiment go?"
"Overall, it was a success."
Naruto replied with a smile before casting Rapid Healing on Itachi.
Rapid Healing primarily restored physical health and external injuries, but Naruto wanted to test whether it could alleviate the strain on Itachi's Sharingan.
Itachi's premature death stemmed from two main causes. First, the psychological burden of wiping out his clan, keeping secrets within the Akatsuki, and being hated by Sasuke for years, which manifested as a chronic illness. Second, the overuse of his Sharingan, which took a heavy toll on his body.
If Rapid Healing could mitigate the effects of Sharingan usage, Itachi might live a much longer life.
Once Naruto mastered the highest level of Observation Haki, he planned to guide and help Itachi overcome his mental scars.
If successful, Itachi should be able to live like an ordinary, healthy person.
"What's this?"
Itachi asked as he felt the green aura enveloping his body.
However, before Naruto could answer, Itachi suddenly trembled, "My eyes!"
"What about your eyes?" Naruto asked hurriedly.
"I feel a cooling sensation in my eyes. They seem to have improved slightly. My energy and blood flow also feel significantly revitalized." Itachi replied in astonishment, "However, it's not as miraculous as the daytime Weapon Blessing that restored my vision completely. Still, this is impressive. I didn't expect you to develop such an extraordinary power, Naruto-kun. If I'd known, I'd have volunteered for the experiment myself."
Hearing this, Naruto couldn't help but feel a little deflated.
'The improvement was minimal, far from enough.'
'As expected, the consumption of Sharingan is not in HP, but in MP.'
In Naruto's memory, games like DNF had other augmentation skills, but without help from the system, acquiring the right skill was like searching for a needle in a haystack.
"Don't worry, Itachi. I'll find a way to fully restore your Sharingan." Naruto said, patting Itachi's shoulder.
"Naruto-kun, I'm not worth this much effort. Why are you so determined? Could it be that you've seen my future?" Itachi asked, his expression calm but curious.
Naruto nodded and said, "That's right. If you keep using your Sharingan at this rate, you'll only have two or three years left to live. But don't worry. You're my servant, and as long as I'm alive, you won't die."
As he said that, Naruto reached into his pocket and pulled out a golden coin, "Do you know what this is?"
"What is it?"
Itachi examined the coin closely, even activating his Sharingan, but he couldn't discern its nature, "Even the Sharingan can't fully see through it. It's radiating intense life energy."
"This is a resurrection coin. After using it, it can bring someone back to life in perfect condition. Of course, I'm keeping it for emergencies, but it's also a guarantee for you. Even if I can't find a way to save you within two years, I'll use this to bring you back."
This was the first time Naruto revealed his trump card.
He rarely disclosed such secrets, but Itachi was his servant, someone who could never betray him. So sharing this information with Itachi brought him peace of mind.
Even if he couldn't obtain a system reward to restore Itachi's Sharingan in two years, he had a contingency plan to ensure success.
And that plan is...