Leisure time always feels short.
After a seven-day vacation, Kakashi returned to his usual training spot.
"Kakashi, Lin, you're here," Tsunade greeted, nodding slightly at the two in front of her.
It had been over two years since she first began teaching them.
Gone were the youthful immaturity and naivety they once carried. Now, both Kakashi and Lin exuded the calm professionalism of seasoned medics.
Kakashi's growth was undeniable. His progress in both medical ninjutsu and general combat skill had far exceeded expectations.
Lin, too, had proven herself. Her talent for Chakra control was extraordinary.
Through relentless day-and-night study, she had thoroughly grasped basic and intermediate medical knowledge. Even more impressively, she had successfully mastered the A-rank medical ninjutsu—Healing Jutsu!
In the ninja world, the difficulty of a jutsu determines its rank. Most village shinobi who master A-rank techniques are already Jonin-level or higher.
Learning A-rank ninjutsu typically requires two things: a strong family background or inheritance of secret techniques, and enough merit to earn contribution points to unlock access. It's not something ordinary ninjas could dream of achieving easily.
More importantly, these jutsu demand excellence in at least one fundamental skill.
Take Naruto's signature move, the Multiple Shadow Clone Technique, for instance. The sheer amount of Chakra required to use it safely makes it lethal for most shinobi. Without an enormous Chakra reserve, overuse could easily lead to death by depletion.
Healing Jutsu is no different. What makes it so rare is its near-impossible requirement for perfect Chakra control.
But Lin had a natural gift.
Over the past two years, she had devoted nearly all her free time to practicing the precise manipulation of Chakra water spheres. Her control became so refined that she could suture wounds while simultaneously operating two Chakra water spheres—each shaped like Kakashi and Obito—and make them spar atop her shoulders!
Even Tsunade was shocked the first time she witnessed Lin's multitasking feat.
From the moment Lin successfully executed Healing Jutsu, Tsunade officially accepted her as a direct disciple.
"After more than a year of continuous study, you've both met the fundamental requirements to become medical ninjas," Tsunade said, her voice serious but tinged with pride.
"So starting today, you and Shizune will begin internships at Konoha Hospital."
"You'll practice in the hospital during the day and study advanced medical theory with me at night. Only by applying your knowledge in real-world scenarios can you grow into full-fledged medical shinobi."
"Yes, Sister Tsunade!" Kakashi and Lin replied in unison, exchanging a glance full of determination.
Before Tsunade could speak again, a cold, hoarse voice interrupted.
"Tsunade, have you reconsidered my offer?"
Kakashi turned to see none other than Orochimaru.
"Things aren't progressing as expected in the experiment. I really need your help."
Experiment? Kakashi's eyes narrowed.
After the Second Great Ninja War, Konoha's strength was severely weakened. The loss of the Kage-level ninja known as the White Fang had only made things worse.
Desperate to restore its former glory, Konoha began the infamous Wood Style Experiment—an attempt to recreate the power of the First Hokage, Hashirama Senju.
At this stage in history, the experiment was a legal, sanctioned project approved by the village leadership and the Third Hokage himself.
Those from the Senju Clan who volunteered for the experiment were inspired by the Will of Fire—fueled by a deep sense of duty to protect the village.
Unfortunately, the First Hokage's cells were far too potent and uncontrollable.
Not a single successful case had emerged so far. Every test subject ended up being consumed by the foreign cells, turning into grotesque trees.
Although the Wood Style experiment was a top-secret matter, Kakashi and Lin were not ordinary students. As Tsunade's direct apprentices, both possessed high-level clearance and were trusted implicitly.
After Orochimaru first brought up the subject, Tsunade had made it clear that the topic was to remain confidential. But over time, she no longer hid the discussion from them.
"Orochimaru," Tsunade's eyes darkened, "I've told you before—while I won't stand in the way of what's been approved by the village, I refuse to participate in anything that risks the lives of my people."
Tsunade's tone was harsh, almost disdainful.
As one of the top medical ninjas in the world, Tsunade wasn't inherently opposed to human experimentation. On the contrary, she believed it was a necessary path for the advancement of medical knowledge.
But that didn't mean she accepted reckless experimentation.
Especially not with Hashirama's cells.
Having seen the immense power of her great-grandfather's Wood Style firsthand, Tsunade had always been skeptical that anyone else could survive, let alone control it.
So far, she'd been proven right.
The Senju clan members who offered themselves for the cause had perished one after another.
To Tsunade, the higher-ups were treating these shinobi like disposable tools. Their obsession with strength had blinded them to the ethics and consequences.
"If you truly won't help, then perhaps Kakashi can be my assistant instead," Orochimaru said, licking his lips as he shifted his gaze.
His tone was calm, but his eyes glittered with ambition.
After so many refusals, Orochimaru had accepted Tsunade's position. But Kakashi—talented, intelligent, and already knowledgeable in advanced medical techniques—was the true target of his visit.
"Absolutely not!" Tsunade snapped. "I won't let Kakashi anywhere near that experiment! Don't even think about it!"
But Kakashi suddenly stepped forward.
"Sister Tsunade, I... actually want to give it a try."
"What?" Tsunade's expression changed instantly. Her sharp eyes locked onto his.
"Kakashi, do you understand what's involved? The risks you'll face if you get involved in this?"
Her voice was filled with urgency. She needed to know—did her student also believe that sacrificing comrades for the sake of power was justifiable?
Kakashi didn't flinch.
"Sister Tsunade, if this experiment truly can't be stopped…"
"Then maybe I can use the medical skills you've taught me to reduce the number of casualties. Even if I can give just one person a better chance at survival—it's worth it."
Tsunade stared at him for a long time.
There was no arrogance or recklessness in his words. Just resolve. Compassion.
In truth, she couldn't refute his reasoning.
If the experiment continued with or without her, having Kakashi as a skilled medical assistant could actually save lives.
From the corner, Orochimaru stayed silent, but his fascination with Kakashi deepened.
After a long pause, Tsunade let out a sigh—half helpless, half resigned.
"Very well. If you're determined to help, I won't stop you."
"But," she added, "you must attend every night's advanced medical training without fail. That's non-negotiable."
She paused again before continuing.
"If you encounter any issues during the experiment that you can't solve, bring them to me during class. I'll help you then."
She waved her hand, signaling that Kakashi could go.
"Yes, Sister Tsunade!" Kakashi bowed slightly and let out a breath of relief.
Now that she had given her consent, he could participate in the Wood Style project openly and gain direct access to the mysterious and powerful Hashirama cells.
Without another word, Orochimaru turned and left, a faint smirk tugging at his lips.
Kakashi followed close behind.
As he walked away, a voice called out from behind.
"Orochimaru… whatever happens—protect him."
Orochimaru paused.
Tsunade's voice held a familiar pain. These were the exact words she had once said before sending her younger brother Nawaki on a mission—one that ended in tragedy.
That time, Orochimaru had failed to keep his promise. Nawaki never came back.
"I understand, Tsunade," he replied without turning around.
This time, I won't break my promise.