Hiruzen asked.
"Feng Zheng, do you know what a vacuum is and its characteristics?"
Feng Zheng fell into deep thought.
"Was vacuum taught in school? Probably not, but the Library might have some related information."
Feng Zheng replied.
"A vacuum is basically a space with nothing in it, not even air. As for its properties, I'm not entirely sure. But I have some guesses, I wonder if they're correct?"
Hiruzen said.
"Indeed, tell me your guesses."
Feng Zheng replied.
"Since there's nothing in a vacuum, the pressure inside should be very low, perhaps even non-existent. So, if something approaches a vacuum, it would be quickly sucked into it. However, in that case, the vacuum would no longer be a vacuum."
Hiruzen was satisfied with this answer. He nodded and said.
"Very good, Feng Zheng. You are right. That's how a vacuum works. The Wind Vacuum Technique is also based on the same principle."
Feng Zheng listened carefully as Hiruzen explained.
"The Wind Vacuum Technique and ordinary Wind Release Ninjutsu are the same; the only difference is that they have a Vacuum Core. So, you must first learn how to create a Vacuum Core. Observe carefully."
Hiruzen extended his arm forward. Wind formed in his hand, similar to the Wind Blast Technique. Feng Zheng watched intently.
A Wind Ball formed in Hiruzen's hand. But soon, the wind began to move away from the core. Feng Zheng saw a spherical vacuum form in the center of the Wind Ball. Its radius was 2 centimeters.
Hiruzen explained.
"To create a vacuum, you simply need to remove all air from the space where you want to create the vacuum."
Feng Zheng nodded. The basic principle was similar to that on Earth. Only Chakra replaced technology.
Hiruzen dispelled the Ninjutsu. Feng Zheng noticed that the wind quickly rushed back into the vacuum sphere. Hiruzen said.
"Now you try, Feng Zheng."
Feng Zheng extended his hand forward. A Wind Ball immediately formed in his hand. He focused his attention on the center of the sphere and tried to move the air out of it.
He quickly succeeded in moving the air to one side of the center. But soon, air from other directions rushed in.
Hiruzen observed him carefully.
Feng Zheng struggled for a few minutes before making progress. He successfully pushed the air in the center out in all directions!
Slowly, a 1-millimeter vacuum sphere formed. Hiruzen noticed, his eyes wide!
Feng Zheng did not see Hiruzen's expression. All his attention was focused on the Vacuum Core.
He kept trying to increase its size. He managed to enlarge it, but always failed. He kept at it.
Hiruzen watched in shock. He sighed in his heart.
"Talent! Danzo took a week to create a stable core. At Feng Zheng's current pace, he can do it himself today!"
Recovering from his shock, Hiruzen analyzed the young man before him.
"This boy was very talented in school, but he didn't show anything special. Besides his relatively large Chakra reserves, all his progress was the result of diligent effort. According to Genshu, even his large Chakra reserves were the product of hard training."
"Even his talent for Wind Release Ninjutsu wasn't that outstanding. Could it be that, like some Ninja, some of his talents only manifest later?"
Hiruzen analyzed further.
"Yes, there are many such Ninja in Hidden Mist and Kumogakure who show Water Release or Lightning Release talent when practicing B-rank or higher Ninjutsu. However, similar cases are very rare in Fire, Earth, or Wind Release."
Hiruzen highly valued Feng Zheng's talent. He expected Feng Zheng to become at least an Elite Jonin.
However, he still underestimated Feng Zheng's talent. After his death, Feng Zheng's talent in Wind Release would reach a level that the world would call a disaster!
Feng Zheng did not know how much of a shock he had given Hiruzen. All his attention was focused on the Vacuum Core.
Creating a Vacuum Core required extremely high Chakra control and extremely high Wind affinity.
Several times, he successfully increased the radius of the vacuum sphere to 5 millimeters before it collapsed.
Ten minutes later, he finally succeeded in creating a stable Vacuum Core with a radius of 1.2 centimeters!
Hiruzen's eyes widened in shock again! He let out a sigh of relief, thinking.
"Fortunately, I placed him under Renjiro. Otherwise, he wouldn't have become a Chunin so early, and his talent would have been wasted!"
Indeed, Feng Zheng was lucky. He had originally planned to spend six years in the academy, building a very solid foundation so that his chances of survival would be higher.
It was only due to the pressure of other classmates passing the graduation exam that he decided to pass the graduation exam early, to avoid unnecessary suspicion.
If not for that, his development would have stagnated for several years. He would have missed the opportunity to rapidly strengthen himself and the chance to be trained by someone of Senju Renjiro's caliber and dedication.
In that case, he would not have had the opportunity to learn the Senju Taijutsu Style and Wind Vacuum Ninjutsu. Although he would eventually learn these skills, his progress might have been delayed by about three to four years!
Hiruzen looked at the Vacuum Core and said.
"Very good, maintain it for two minutes."
Feng Zheng did not reply, only did as he was told. He was able to maintain it for a full 2 minutes. Hiruzen was shocked again. He said.
"Now, envelop it with wind, aim at a tree, and then launch it like you would a Wind Blast Technique."
Wind immediately began to form around the Vacuum Core, taking on a spherical shape.
Feng Zheng looked at a tree and threw the vacuum sphere. However, as soon as the Wind Vacuum sphere left his hand, the Vacuum Core began to collapse.
When it traveled one meter, the Vacuum Core collapsed, and air entered it. The Wind Vacuum sphere then collapsed and dissipated.
Feng Zheng exclaimed in surprise.
"What's happening?"
Hiruzen glanced at it and said.
"You successfully maintained the Vacuum Core after creating it. However, when you launched it, you could no longer maintain it. So the surrounding air entered the Vacuum Core, and your Ninjutsu collapsed."
Feng Zheng analyzed Hiruzen's words and nodded. He asked.
"Then how do I maintain the vacuum sphere when it moves away from me?"
Hiruzen created another Wind Ball with a Vacuum Core and said.
"Observe the movement of the wind around the Vacuum Core carefully."
He slowly shot the Wind Ball towards a large rock. Feng Zheng observed carefully.
"Incredible. The way the wind moves prevents air from entering the Vacuum Core! And, there seems to be a thin layer of Chakra separating the wind from the Vacuum Core."
The Wind Ball hit the boulder. The wind only caused some scratches.
However, when the Vacuum Core touched the boulder, the part it touched turned into dirt and was sucked into the Vacuum Core.
The Vacuum Core continued to advance for about ten centimeters, absorbing everything around it, and then disappeared.
It left a hole in the boulder twenty centimeters deep and ten centimeters wide!
Hiruzen explained.
"To maintain a Vacuum Core, you need to do two things. First, you need to form a thin Chakra membrane around the Vacuum Core to ensure that nothing enters it. Then, you need to rotate the wind around this membrane so that it neither damages the thin Chakra membrane nor allows external air to touch the Chakra membrane."
"When the Ninjutsu hits the target, the wind first causes minor damage to the target, followed by the Vacuum Core hitting the target. Since the Chakra membrane is very thin, it will break upon contact with any solid or even liquid. Once broken, the Vacuum Core will absorb anything it touches, no matter how hard the target is. When the Vacuum Core passes through, it looks as if the object has been cut in half. But this is not a simple cut."
Feng Zheng nodded. This Ninjutsu was extremely lethal.
Hiruzen continued.
"When you cut a person with a sword, only a wound forms on their body. As long as that person doesn't die on the spot, a good Medical Ninja can easily heal them. Even severed arms or legs can be reattached. But with the Wind Vacuum Technique..."
Hiruzen pointed at the hole in the boulder and continued.
"The Vacuum Core absorbs everything within a ten-centimeter diameter. Very few Medical Ninja can heal such a wound. If it hits any organ, such as the stomach or liver, those organs will be destroyed on the spot, and survival is almost impossible."
Feng Zheng nodded. Hiruzen's explanation was exactly as he had observed. He thought to himself.
"Excellent! The Wind Release: Vacuum series of Ninjutsu is too powerful. I finally have a way to break through enemy defenses."
He looked at Hiruzen and said.
"I understand why you asked me not to use this technique on comrades, Hokage-sama."
Hiruzen smiled and nodded. He just wanted Feng Zheng to understand the dangers of these Ninjutsu. He said.
"The basic theory is clear. Now, try it yourself. Begin."
Feng Zheng nodded and began to focus intently on creating another vacuum sphere.