Feng Zheng began his training. Hiruzen temporarily had him practice creating a Vacuum Core with a one-centimeter radius.
After creating the Vacuum Core, he began to wrap it in a thin layer of Chakra. This required precise Chakra control.
However, with the training from the Senju Taijutsu style, his Chakra control was already excellent.
After a few failures, he quickly learned it.
The next challenge was to form a wind layer around it, and this time he failed more often. As soon as the wind touched the Chakra membrane even slightly, it would collapse. But soon, he successfully created a proper Wind Ball.
In Feng Zheng's right hand, a Wind Ball spun. At the center of this Wind Ball was a thin Chakra membrane, enclosing a Vacuum Core with a 1 cm radius. Hiruzen thought.
"This is incredible. He mastered the basic form in less than 10 minutes!"
Hiruzen said.
"Now throw this ball at a tree."
Feng Zheng nodded and followed his instructions. After flying ten meters, the Vacuum Ball suddenly began to collapse. Feng Zheng observed carefully and muttered.
"The wind layer touched the Chakra membrane and entered the Vacuum Core."
Hiruzen nodded and said.
"That's right. You need to ensure that even during flight, the wind layer doesn't touch the Chakra membrane. And you also need to make the Chakra membrane stronger without increasing its thickness."
Feng Zheng nodded and began to train again.
For the next 7 hours, Feng Zheng continuously experimented with the flow of wind, trying to make the Chakra membrane stronger.
Hiruzen observed from the side. Due to Feng Zheng's dedication and diligence, he initially looked at Feng Zheng with affection. However, after 7 continuous hours, he sighed.
"I thought he would take a break to eat breakfast and lunch. Instead, he just grabbed a few ration bars and stuffed them into his mouth! He didn't even share any with me."
Hiruzen hadn't brought any food. Several times, he asked Feng Zheng to take a break. However, Feng Zheng replied.
"Give me a little more time, Hokage-sama. I think I'm almost there!"
After replying, he immersed himself back in practice, not even looking at Hiruzen.
He did chat with Hiruzen a few times, but only about problems in his training. After getting answers, he would again focus on his training.
Finally, he mastered the trick! He created another Vacuum Ball and threw it into the air. It flew about 100 meters before collapsing.
Feng Zheng looked at Hiruzen, who nodded and said.
"Very good. Now try it on a tree or a boulder."
Feng Zheng nodded and followed his instructions. He created a Vacuum Ball and threw it at a tree. It hit the tree and pierced through it, creating a 5-centimeter wide hole in the tree.
He smiled happily and began to create more Vacuum Balls. In the next few minutes, dozens of trees were pierced. However, each Vacuum Ball collapsed after piercing a tree.
Feng Zheng thought.
"This is good, but if it collapses so quickly after piercing a tree, it's not as lethal. Perhaps creating a larger Vacuum Core ball might be more durable..."
Hiruzen didn't know Feng Zheng's thoughts. Watching his performance, he praised him.
"Feng Zheng, well done today, but let's stop here for today."
Feng Zheng looked at Hiruzen and protested.
"But Hokage-sama, I can still train!"
Hiruzen shook his head and said.
"Your Chakra is almost depleted, and if you train any more, you might not be able to train tomorrow. The next training will be as challenging as today, so let's stop here for today."
Feng Zheng nodded helplessly. Hiruzen instructed.
"Don't practice Wind Vacuum Technique when I'm not around. And it's best not to use any Ninjutsu today. Meditate and recover your Chakra as soon as possible. We'll meet again tomorrow morning at seven."
Feng Zheng nodded and thanked Hiruzen for his guidance.
Hiruzen smiled and left, thinking.
"Finally, I can eat something! I didn't expect him to train for so long continuously. After training for a few hours, his teammates left. However, he can complete the basic version of the Wind Vacuum Technique in a third of a day! Feng Zheng is very talented in Wind Release."
He smiled and thought.
"How will Danzo react when he finds out an 11-year-old learned in 8 hours what he needed 9 days to learn!"
After leaving, Feng Zheng went to the Ninja shopping district. He walked into the same clothing store as a year ago.
Feng Zheng asked the Restaurant Owner to make him clothes similar to what he was currently wearing, but tailored to his current size.
The Restaurant Owner measured Feng Zheng and said.
"Child, you're growing fast, you've grown 10 centimeters taller in less than a year!"
Feng Zheng said.
"Yes, thank you."
The Restaurant Owner smiled and said.
"I saw you in the Chunin Exams. You performed excellently! Congratulations on winning the match."
Feng Zheng nodded. After taking his measurements, the Restaurant Owner asked.
"I have a product to show you, most Ninja buy this from me."
Feng Zheng asked curiously.
"What product is it?"
The Restaurant Owner picked up a box and opened it. He took out something that looked like chainmail.
Feng Zheng took it and examined it. It felt very sturdy!
Without being enhanced by Chakra flow, it should be able to block incoming Shuriken and kunai. This might also reduce the damage caused by Shuriken and kunai thrown directly at him.
Combined with the Chunin vest and shirt, ordinary Shuriken would probably find it difficult to cause harm. Of course, other parts of the body were still vulnerable.
The Restaurant Owner said.
"This is an upper body mesh armor, it's..."
Feng Zheng interrupted him and said.
"I want two sets of this as well."
The Restaurant Owner nodded and said.
"Okay, it will probably take us about a week to get everything ready for you. Come back and see me in a week."
Feng Zheng nodded and left.
The next day, Feng Zheng began to warm up again, waiting for Hiruzen's arrival. Hodaka, Mieko, and Hiruzen all arrived before 7 AM.
The group split up again, with Hiruzen's main body still staying with Feng Zheng.
Hiruzen instructed.
"First, review what you've learned so far. Use a few Vacuum Balls on that boulder."
Feng Zheng followed his instructions, throwing several Vacuum Balls at the boulder one after another. The first pierced most of the way through, and the second pierced straight through.
Hiruzen said.
"Very good. After yesterday's training, what is your experience with the Wind Vacuum Technique so far?"
Feng Zheng thought for a moment and said.
"In terms of penetration, it is very strong. However, the Vacuum Core quickly collapses after hitting the first target. So, even if this technique can penetrate any defense, it cannot harm anything hiding behind the defense."
He looked at Hiruzen and continued.
"I wonder if increasing the size of the Vacuum Core could solve this problem."
Hiruzen replied.
"Good analysis. But no. Once the Vacuum Core starts to absorb, it will quickly collapse."
Feng Zheng frowned and thought.
"I don't remember clearly, but Danzo's Wind Vacuum Technique seemed to be able to continue moving after piercing a rock. Why isn't it like that now?"
Seeing Feng Zheng frowning in analysis, Hiruzen smiled. He said.
"However, there is a way to solve this problem, to make the Wind Vacuum Technique last longer and hit multiple targets along its path."
He extended his right arm towards a tree and said.
"Watch closely."
Feng Zheng carefully observed the Vacuum Ball forming in Hiruzen's palm. His eyebrows furrowed. The Vacuum Core was different, but he couldn't understand how.
Hiruzen launched the Vacuum Ball. It pierced through the tree but maintained its shape and continued forward.
Feng Zheng's eyes widened as he watched the Vacuum Ball penetrate thirteen trees before finally collapsing with a bang! He simply exclaimed.
"Wow!"
Seeing Feng Zheng's reaction, Hiruzen smiled with satisfaction. Feng Zheng asked.
"The Vacuum Core looks different, what did you do?"
Hiruzen extended his arm forward and said.
"Observe more closely."
A small Vacuum Core slowly formed in Hiruzen's palm, forming a 1cm radius Vacuum Core. Then a thin layer of Chakra wrapped around it.
However, instead of wind forming around the Chakra membrane, a vacuum began to form!
As the vacuum formed, Chakra began to extend from the Chakra membrane. The vacuum outside the Chakra membrane completely enveloped it but was divided into six equal parts.
Between these six parts, Chakra also flowed. Moreover, within these six vacuums, there were also thin Chakra threads similar to veins.
Hiruzen walked towards a nearby tree, saying.
"Come with me, and observe carefully what happens after it hits the tree."
Feng Zheng followed behind him. Hiruzen slowly pressed this Vacuum Core against the tree trunk.
The tree trunk began to disintegrate and was absorbed by the vacuum. But after entering the vacuum, it was directed towards the Chakra between the vacuums. After entering the Chakra flow, they were thrown out of the Vacuum Core.
Feng Zheng was very surprised. He said.
"The absorbed material is thrown away. So the Vacuum Core is maintained. And the innermost Vacuum Core is not hit at all."
Hiruzen dispelled the Ninjutsu and nodded.
"Yes, this way your Vacuum Core will last longer. Once you master this, your enemies will have to dodge your Ninjutsu, because blocking them with objects is almost impossible."
Feng Zheng nodded and smiled.
"This looks very lethal! Thank you, Hokage-sama!"
Hiruzen smiled and said.
"Now you try to create such a Vacuum Core."
Feng Zheng nodded and began to train.