`The next day, Sakura Haruno began her formal training.
Tsunade brought her to a fresh market outside Tanzaku Street, buying a bunch of live fish.
"What do you think medical ninjutsu is?"
Tsunade, having heard from Jiraiya about Sakura's genius, tested her with the question.
"No clue!"
Sakura answered bluntly. She'd read the notes Tsunade gave her, but to her, medical ninjutsu felt more like a science—covering techniques, pharmacology, pathology, clinical practice, and more.
As a newbie, she figured it was best not to make assumptions about an unfamiliar field. That was her basic humility as a learner.
Tsunade paused, then said, "In other people's eyes, medical ninjas can't fight, their techniques are tough and complex, and the knowledge is vast and tedious. Learning it is a bumpy road because they don't grasp the essence of medical ninjutsu!"
Tsunade raised a finger and tapped Sakura's forehead. A green chakra glowed, and a warm current flowed from her finger into Sakura's body.
"The essence of medical ninjutsu is simple. It's just ninjas using their Yang Release chakra. All the techniques are just variations of that chakra's properties!"
Tsunade had explained it so clearly that Sakura got the gist.
"The essence of ninjutsu?"
Hearing Sakura's musing, Tsunade's eyes lit up. "Exactly!"
"Chakra is a balanced mix of two energies. When you extract it, you inevitably draw on the body's life energy. By isolating that energy from chakra to stimulate a patient's cells, you get the foundation of medical ninjutsu!"
"So, the core of medical ninjutsu lies in how precisely a ninja can control their chakra. The finer the control, the more life energy you can extract, and the better the results!"
"But you've got to be careful—stimulating cells can also drain a patient's vitality, so training in medical ninjutsu is all about mastering delicate control."
After explaining the essence, Tsunade stood and pulled a small jar from between her… assets.
She poured its contents into a bucket of live fish. The paralyzing toxin entered their bodies, and the whole bucket of fish floated belly-up.
"Today, I'll teach you the easiest medical ninjutsu—a B-rank technique: Delicate Illness Extraction."
Tsunade grabbed a fish, formed hand signs, and gathered the toxin in its body into her hand, forming a small droplet.
"Your task today is to extract all the toxin from that jar without killing the fish."
"Can you keep up? If not, I might just send you back!"
"No worries! There's no ninjutsu in this world I can't learn!"
Sakura had already used her Observation Haki to track every detail of Tsunade's chakra flow. Mimicking her, she tried separating the life energy from her chakra, and a green glow appeared in her palm.
Taking a few steps forward, she grabbed the fish from Tsunade and started practicing.
Watching the girl train diligently, Tsunade hopped onto a nearby rooftop.
Her longtime student, Shizune, arrived with a jug of sake.
"Lady Tsunade, you're being kinda mean."
Shizune, holding her pet pig Tonton, looked at the girl below with pity.
"Delicate Illness Extraction may be low-difficulty, but its demand on sensory skills is on par with A-rank medical ninjutsu!"
"Hmph, I'm trying to make her give up."
Tsunade sipped her sake, nibbling on dried fish.
"Jiraiya just dumped his student on me without a word and acted all smug about it. I couldn't exactly say no."
"So, I picked a technique with a hidden challenge to trip her up. A genius like her will back off once she realizes it's tough."
Feeling clever, Tsunade downed the whole jug of sake, mentally patting herself on the back.
"Huh? I did it!"
Sakura placed the detoxified fish back in the bucket. The entire jar of poison Tsunade had poured in was now completely extracted.
Holding up the wriggling fish, Sakura waved at the stunned Tsunade on the rooftop.
"Big Sis Tsunade, look, I nailed it!"
"Shizune!"
Tsunade's eyes narrowed. The pink-haired girl was growing on her.
She was sweet-talking, cute, a gambling prodigy, and insanely talented at medical ninjutsu.
Damn it, how did that perverted creep Jiraiya snag such a perfect kid?!
But it was fine—she was willing to learn medical ninjutsu. This was Tsunade's chance!
"What's up, Lady Tsunade?"
Confused, Shizune leaned in, bringing her ear closer.
"Would you mind having a junior sister?"
Tsunade chomped on her salted dried fish, making a crunching sound.
"Huh? Didn't you just say you didn't want to take on students?"
"Well, now that I think about it…"
Tsunade's mind was already racing with fantasies of taking this girl under her wing.
The two of them hitting the casinos—Sakura raking in the cash, Tsunade living it up!
Wiping drool from her mouth, Tsunade leaped down from the rooftop.
"You're… Sakura, right?" Tsunade coughed, covering her mouth with her fist. "Wanna learn some really advanced medical ninjutsu?"
"More advanced?"
Sakura had a hunch about Tsunade's intentions but widened her innocent emerald eyes anyway.
"Yup, a technique that can heal hundreds of people at once!"
Taking a deep breath, Tsunade's face lit up with pride.
During the Ninja World War, she'd single-handedly healed hundreds of poisoned ninjas, thwarting the Sand Village's attack on Konoha.
"I'm in!"
Tsunade was offering to teach, and Sakura wasn't about to say no.
With Sakura's approval, Tsunade didn't hesitate. She clapped her hands together and bit her finger.
"Summoning Jutsu!"
Her palm hit the ground, and seeing the streak of blood, her body trembled.
She staggered backward, nearly falling, but something emerged from the smoke, catching her just in time.
"Lady Tsunade?"
"Been a while, Katsuyu."
Tsunade, a bit weak, raised her hand and touched the slug. Its chakra surged into her fingers, instantly healing her wound and cleaning the blood.
"What's the reason for summoning me?"
"I found a promising kid. See if she's worthy of signing the Shikkotsu Forest summoning contract."
Feeling a bit better, Tsunade waved Sakura over to meet Katsuyu.
"Oh, another spirited child~"
Katsuyu slithered onto Sakura, its cool, soft body brushing her skin.
"Hmm, you have a pleasant scent… the scent of space-time, isn't it~?"
Facing this ancient sage's fragment, Sakura felt oddly nervous.
Those mottled eyes seemed to peer through all her secrets.
As Sakura squirmed under the gaze, Katsuyu spoke up. "You're a good kid. I like you~ Let's sign the contract!"
As it spoke, Katsuyu opened its mouth, spitting out a scroll from its abdomen.
"Just write your name on it and drip some blood."
Katsuyu's gentle voice guided Sakura through the summoning contract process.
When Sakura's blood hit the scroll, Katsuyu's calm tone gained a hint of joy.
"Then, from now on, we're partners in battle, Lady Sakura!"
"Of course, I'm thrilled to be your partner, Sage Katsuyu!"
"Ohoho~ Such a clever child."