The Third Hokage had just said that to pass the graduation exam, you first had to pass a written test. The written test covered material from the textbooks.
As a ninja village, Konoha didn't place much importance on book learning. It cared more about a ninja's combat ability. So even a cat or dog could pass the written test without much trouble. Otherwise, wouldn't Naruto have been stuck in the academy for the rest of his life?
Each year, the graduation exam covered one of six subjects: basic Taijutsu, basic Shurikenjutsu, genjutsu dispelling, Substitution Technique, Transformation Technique, or Clone Technique. If a class was lucky, the test might be on Transformation Technique, Clone Technique, or Substitution Technique. If they were unlucky, it might be on something like genjutsu dispelling or Shurikenjutsu.
Yashui had known for a long time that this year's exam would be on Clone Technique, which he could already use with ease.
But the Third Hokage wasn't easy to fool. If Yashui wanted to graduate early, he'd have to take more tests than the other students. That was why Asuma had been sent to test him.
Unless something unexpected happened, Asuma would test him on all six subjects.
Basic Taijutsu, basic Shurikenjutsu, and Clone Technique weren't difficult for Yashui. They were all among his strengths.
As for genjutsu dispelling, Yashui only had to quietly activate his Sharingan. Even without doing anything else, the Sharingan's inherent resistance to genjutsu would be enough to pass the test.
The problem was Transformation Technique and Substitution Technique. The Hand Seals for both were simple, and they were easy to pick up. But using them in actual combat took a lot more practice. Even an ordinary ninja would need at least a week of training.
The tricky part of Transformation Technique was having the right sense of scale. Children perceived height and width differently from adults. When they transformed into adults, their subjective sense of an adult's height and width could make the transformation look unlike the original. It took practice to correct that.
Substitution Technique, on the other hand, was a low-level Space-Time Ninjutsu that used very little chakra. It let the user switch places with a target. Though it was said to "dodge any attack," it was actually difficult to use and came with plenty of restrictions.
First was the change in perspective after using Substitution Technique. Some ninjas might move too quickly or choose a substitute at random, then lose track of where they were. It was like getting carsick; the only way to get used to it was through practice.
The second—and biggest—difficulty and flaw of Substitution Technique was that the substitute had to share some feature with the user. For example, the logs that appeared most often in the original work could be used because they were roughly the same size as the user.
But you couldn't find something that had something in common with you everywhere you went. Sometimes it took quite a while to find a suitable substitute, and the only way to get faster at it was to practice more.
On the battlefield, it was often hard to find something suitable to substitute with. Some ninjas raised animals or used clones, turning them into substitutes. But most ninjas had to make do without.
So it wasn't that people stopped using Substitution Technique toward the end of Naruto. It was that the battlefield had changed, and they couldn't use it anymore. (Trying to excuse Kishimoto's failed worldbuilding...)
In short, it wasn't realistic to master these two jutsu well enough to use in combat in a single day, when both required so much practice.
Then Yashui remembered that whenever he used the Sharingan, he would instinctively learn things he hadn't known before or wasn't good at. It was almost as if he'd gained someone else's memories and skill...
There was no other choice. He didn't know how it worked, but if it could help him graduate a year early, it was worth a try.
After dinner, Yashui shut himself in his room and drew the curtains, leaving the place pitch-black. Ever since Konoha Anbu had taken him away the day before, he'd been very cautious even when alone in his room. He tried not to turn on the lights unless he had to.
Yashui gathered some chakra and activated his Sharingan. The once-dark room suddenly came into clear view. The Sharingan really did improve his eyesight.
"Substitution Technique, Transformation Technique... Substitution Technique, Transformation Technique..." Yashui repeated the words over and over in his mind. Three minutes later, the knowledge related to both jutsu flowed into his mind.
Once he had what he wanted, Yashui deactivated his Sharingan. As a kekkei genkai of the Uchiha Clan, the Sharingan consumed a lot of chakra.
"Transformation Technique!" Yashui turned on the light and used the jutsu in front of the mirror.
"Poof!" When the smoke cleared, someone who looked exactly like the Third Hokage appeared in the mirror.
"The Transformation Technique worked perfectly." Yashui felt more at ease about the test the next day. "Next, Substitution Technique."
Yashui looked around, but there was nothing he could use as a substitute.
"Should I try a toy?" Yashui glanced at a life-size Enma doll in the room.
"Substitution Technique!" Yashui formed several Hand Seals and immediately performed the jutsu.
Another cloud of smoke appeared. When it cleared, Yashui and the Enma doll had switched places.
He'd handled both jutsu with ease. He should be able to pass Asuma's test too.
Seeing how easily he'd "learned" all these jutsu, Yashui lay down on the bed, content.
"No, everything since I entered this world has gone far too smoothly. If I keep using these shortcuts to gain power, I'll get used to having things handed to me... I'm already getting a little lazy..." Yashui felt a sense of danger. "From now on, I should try not to rely on the Sharingan."
On the path outside the Third Hokage's house, Asuma and the Third Hokage were taking a leisurely stroll.
"Dad, you don't have to walk me out. You should go back. You still have to look after Konohamaru and Yashui." Asuma lit a cigarette and took a deep drag.
"It's fine. They're both very independent kids. In seven or eight years, we'll have to rely on them to hold Konoha together." The Third Hokage took out his pipe too. "Asuma, when will you start smoking like an adult?"
"Everyone smokes cigarettes like these now. It's progress."
"By the way, what do you think of Yashui?" The Third Hokage abruptly changed the subject. "That boy suddenly asked to graduate early."
"Don't worry. I'll make the test as difficult as I can tomorrow," Asuma said, seeming unconcerned. "Uchiha Yashui has been spending a lot of time with Sasuke Uchiha lately. The Uchiha Clan's tendency to band together nearly brought disaster to Konoha once before. Now those two are so close—could it..."
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