Little Tsunade didn't understand the future. Right now, she was just happy. Because she really, truly liked medical arts. And, as it turned out, there really were things in the world just as compelling as gambling.
Although Shirou's arrival meant she spent less time fleecing her great-grandfather at dice, his presence made her childhood infinitely brighter.
After returning to Konoha, Shirou had to check on Hashirama's condition daily, which meant Tsunade got to see him every day. She loved tagging along behind him, whether it was to the hospital or just wandering the streets of Konoha to buy chestnut juice.
And... Emiya Shirou was exactly like the hero in the stories!
Even better, in fact!
Compared to her great-grandfather, who was endearingly unreliable, Shirou's image was pure gold for a child. When he was treating patients, his focus was intense, almost unapproachable, yet his words were always gentle and considerate. If a patient didn't understand, he'd patiently rephrase, breaking down complex conditions into simple analogies.
His attitude towards ninjas was colder, as if he fundamentally disliked their entire profession, but even then, his warmth would peek through, especially when it came to children.
On the way to the hospital, little Tsunade's short legs struggled to keep up with Shirou's deliberately slowed pace. "It feels so far today," she mumbled, the journey seeming endless to a child.
Shirou glanced down at her, his expression unreadable.
"I'm not tired! I can still walk!" she quickly added, afraid his cool gaze was a sign of disapproval. She waved her little hands to prove her point, terrified that the medical ninja she admired might think her weak-willed.
Without a word, Shirou reached down, lifted her small body, and settled her on his shoulders.
"Whoa!" Tsunade's world suddenly expanded. "It's so high up here! Is this where the slug from the stories sat?"
"Yes," Shirou replied, his tone as flat as ever. "When the slug can't keep up, it also sits on my shoulder."
Tsunade touched her chubby cheek, her mind racing with future possibilities. "I want to raise a slug too someday."
"Mm," Shirou grunted in agreement, his pace quickening. The gentle breeze made her blink.
"Can I learn a lot of things today?"
"Yes."
"Then can I have some of that sweet grape juice today?"
"No," he said, dashing her hopes. "That's for patients." But he offered a compromise. "After you're done studying, you can have a little chestnut juice."
"Hmph," Tsunade puffed out her cheeks in a mock pout.
By now, no one at the hospital was surprised to see Shirou arrive with Tsunade in tow. They all assumed he was teaching a student.
It was the perfect picture: the master and his apprentice. At five years old, she had already mastered basic medical ninjutsu and could handle simple scrapes. But she still had so much to learn.
She would stand by his side, listening with rapt attention as he explained complex illnesses in ways anyone could understand.
"Your own body's resistance is more useful than any medicine. This disease will cause your body to produce antibodies, and you won't suffer from it again."
"Think of some diseases like a fire in your house. To put it out, we use water. From now on, to prevent fires, we'll keep a vat of water ready. Antibodies are like that vat of water, always prepared. You won't have to worry about this disease again."
"So cool..." Tsunade's eyes sparkled. She didn't fully grasp the science, but she understood the core concept: water beats fire.
Only when the sun set and her stomach rumbled would she tug on his sleeve. "Lord Emiya, when can we eat? I want that thick, sweet chestnut juice!"
Shirou would just reach out and gently rub her head. The man was of few words, but he always kept his promises to her.
One evening, as they were leaving the hospital, a small commotion occurred. A handsome little boy with long, dark hair was rushed in for emergency treatment. Food poisoning, apparently, and it looked serious.
For Konoha Hospital, however, this was a trivial matter. A medical ninja quickly induced vomiting, and the crisis was averted.
As Shirou walked past the nervous parents with Tsunade, he overheard the little boy's weak voice.
"Just ordinary green beans and bell peppers... how can they make a body so weak?"
"Honestly, Orochimaru," his mother sighed, exasperated. "You can't keep doing these strange experiments in the kitchen by yourself."
"Alright, alright," his father said, more amused than angry. "Let's just add a new rule to the kitchen's poison registry: green beans and bell peppers don't mix."
Shirou stopped, squatted down, and whispered something to Tsunade.
Just as the medical ninja in the corridor was dutifully recording that green beans and bell peppers were a toxic combination, Tsunade suddenly darted over.
"It's not because they were mixed!" she declared. "It's because the green beans weren't cooked properly. If you don't cook beans all the way through, they make strange things that cause food poisoning."
"Eh?" A group of people stared at the chubby little girl in surprise.
The weak little boy on the chair watched her run out, a flicker of surprise in his narrow, elongated eyes.
Someone knows more than me... and they're my age.
Ever since he was young, Orochimaru had been insatiably curious about the unknown. His scientific journey had begun when he'd accidentally been hospitalized due to his mother's disastrous cooking.
From that day on, he discovered that there were things in the world that could reduce him and the strongest adults to the same state of weakness.
It was fascinating!
A child could defeat an adult!
His first experiments naturally involved the kitchen, the scene of his initial poisoning.
If an experiment failed, it meant the food was safe, and he could serve it to his parents to earn their praise. If it succeeded... well, it meant another trip to the hospital.
But today, in little Tsunade, Orochimaru saw another possibility. There was a kind of knowledge that could more directly identify what was poisonous. Unfortunately, before he could say a word, he watched the chubby, blonde girl walk out of the hospital, holding the hand of a young man.
"Little Tsunade can even remember that kind of knowledge," a medical ninja praised her. "As expected of a child taught personally by Lord Emiya!"
"Little Tsunade? Lord Emiya?" Orochimaru's eyes narrowed.
These two unfamiliar names entered his world for the first time. His gaze followed their departing figures. That young man, his silhouette cast long and dark by the setting sun, had just left the first indelible, inky stroke on the canvas of the little boy's heart.