In the original story, Shizune had taught Sakura about poison.
Later, in an attempt to kill Sasuke, Sakure grazed Naruto's cheek with the poison tipped kunai.
Shortly after, Naruto was immediately affected by the poison, becoming paralyzed and unable to move.
In the ninja world, medical ninjas aren't the only ones who play with poison.
For puppet masters in Sunagakure, applying poison to their puppets is a basic tactic.
Coupled with puppets equipped with various mysterious mechanisms and agonizingly lethal poisons, puppet masters specialize in torturing people.
There's also Hanzō of the Salamander, the man who defeated the combined forces of Tsunade, Orochimaru, and Jiraiya.
His poison is so potent that even Tsunade finds it troublesome.
It can be said that the upper limit of poison is quite high.
However, the required poisons are difficult to find, either biological toxins from within ninja beasts or newly concocted toxins.
Kiyoshi picked up the scroll and chatted with Nono for a while before leaving.
Nono had other matters to attend to and couldn't accompany him at all times.
...
Uchiha compound
"Those Byakugan... She is from the Hyūga clan."
Mikoto, who was returning from grocery shopping, noticed a girl in a maid outfit walking in the distance.
Her head was lowered, and she walked silently through the Uchiha clan's streets, seemingly not wanting anyone to see her Byakugan.
"What is she doing in the Uchiha compound?" Mikoto looked puzzled.
After thinking for a moment, she followed Natsu, wanting to see why a Hyūga would come to the Uchiha clan.
Before long, Natsu stopped in front of a somewhat dilapidated residence and knocked on the door.
"Is Kiyoshi here?"
Natsu was also carrying a basket filled with pastries.
Ginka had her deliver a generous gift first, and then confirm the scheduled time for another visit.
This was the etiquette belonging to the main family.
Every word and action was subject to strict and rigid education, full of the aura of a great clan.
However, Natsu found these rules cumbersome. Fortunately, the branch house was not so strict.
If the main family's education was elite-style, then theirs was ordinary, only having some more secret techniques than ordinary ninjas.
The truly core Gentle Fist techniques of the Hyūga can only be learned and inherited by the main family.
The branch house does not have the qualification to learn them.
"Kiyoshi?"
Natsu knocked again and waited in place for a while.
Unfortunately, there was still no response.
She revealed a disappointed expression. It seemed Kiyoshi wasn't home, this trip was in vain.
She could only go see if Kushina was at her residence.
Mikoto, who was following behind, looked up and saw that this was Kiyoshi's house.
Judging from the girl's appearance, she was probably Kiyoshi's classmate.
'Not bad, this kid.'
Mikoto thought to herself, thinking it was just some young people's affairs.
'Fugaku and I should be getting close too.' Mikoto thought.
If there are no accidents, they will get married within the next year or two.
She hoped that the increasingly tense situation wouldn't affect them.
If a war ocuurs, Mikoto didn't think there would be time to get married.
She wouldn't even have time to retire.
But if they finish everything before the great ninja war, there will still be a chance for her to stay in the rear as a housewife.
Of course, if the war situation gets too bad, even a housewife like her will be affected and she will have to rejoin the war from retirement.
By the time Mikoto came back to her senses, Natsu had already returned with the basket.
Natsu didn't wait for Kiyoshi, Kiyoshi wasn't home.
Mikoto shook her head, laughing at herself for thinking about such distant things.
She walked towards her home.
...
Before returning, Kiyoshi first went to see Kurenai and taught her a few lessons in taijutsu.
After a while, Kiyoshi returned to his home.
He began to browse through the new scroll he had gotten today.
With his knowledge of medical skills as a foundation, Kiyoshi's learning of poison progressed by leaps and bounds, and many things were interconnected.
"You have triggered the Trait: [Apprentice Poison User (White)]."
[Apprentice Poison User (White)]
[Requirement: Master the most basic poisoning method.]
[Progress: 1%]
[Effect: Your accumulation of knowledge in the way of using poison and poisoning is more profound, and the speed of practice is increased by 5% on the original basis.]
[Note: Can be upgraded.]
Kiyoshi closed it and continued to browse through the scroll.
He could fully acquire this trait in one night.
With [Reading Absorption (White)] and [Basic Memory (White)], as well as the accumulated 10% increase in Yin chakra, Kiyoshi's thinking and learning ability had greatly improved.
When he had time, Kiyoshi planned to get the wind release related Trait as well.
The more ninjutsu he learns, the more calm he will be in the face of various geographical environments.
...
"I can go from here."
Hazuki said, looking back.
She and Yamada were standing at the boundary between the Uchiha compound and Konoha street.
"Okay, be careful."
Even though he knew that the Uchiha compound was extremely safe, with the Konoha Military Police Force patrolling, Yamada still said this.
He waved his already healed arm and said goodbye to Hazuki.
Today, Yamada and Hazuki had gone to Nekobaa's place again.
Hazuki also said that in order to cope with the increasingly frequent mission requests, she purchased ten more sets of chainmail.
Yamada was very supportive of this, it was better for Hazuki to be safe.
For him, every day spent with Hazuki was unforgettable.
"...Okay."
Hazuki nodded lightly.
After she couldn't see Yamada's figure under the dim streetlights, Hazuki walked along the edge of the compound.
She was going to find Kiyoshi.
...
"Hazuki-nee, this is your first time coming to my house, right?"
Hearing the knocking sound, Kiyoshi put down the scroll in his hand.
He put the white snake from his arm onto the tatami mat, and went out to open the door.
He had just gotten the [Medical Genin (Green)], and now a genjutsu scroll was about to be delivered to his doorsteps.
[Medical Genin (Green)] had almost the same effect as the [Lightning Release Genin (Green)].
Kiyoshi's Chakra pathway system now had 20% better adaptability to Yang chakra.
Medical ninjutsu is actually a type of Yang Release usage.
Both Yin Release and Yang Release are used very frequently in the ninja world.
Yang Release is used to develop and utilize physical strength.
Yin Release is used to develop and utilize spiritual strength.
These two are much rarer and more advanced than ordinary ninjutsu.
Apart from medical ninjutsu, most of them are secret ninjutsu of ninja clans.
Ordinary ninjas simply don't have access to them.
Medical ninjutsu is already considered a relatively fair, open, and just way to rise and learn.
As long as you have Yang chakra nature, you can pass the preliminary selection of medical ninjas at Konoha Hospital.
If you have some talent in chakra control, then you can formally learn and be taught valuable knowledge.