The "Mayfly Technique" is a unique jutsu exclusive to the Zetsu. It's hard to categorize this jutsu into any specific elemental affinity.
When activated, it allows the user to move freely through the earth, plants, and even underground rivers. It involves earth, wood, and water elements. Essentially, it is an extremely advanced infiltration technique.
Moreover, White Zetsu use this technique silently, without the need for hand seals like ordinary ninjas. It's almost instinctual, or a bloodline limit.
Because of this, countering the technique based on its attributes is nearly impossible. The only option is to catch them off guard.
Even then, it's not an easy task.
Although most White Zetsu lack significant combat strength, there are so many of them that some must be quite powerful. The ones monitoring Konoha are unlikely to be weak; he speculates they should have at least jonin-level strength.
Additionally, White Zetsu have another powerful trait: their life force is extremely strong. Conventional methods find it hard to kill them.
These creatures are not truly human anymore; their essence is closer to plants. Plants can't be easily killed with a single stab.
Thus, capturing and immediately subduing them requires a return to Aoba's current area of study—sealing techniques.
Aoba needs to develop a convenient sealing technique to quickly seal all chakra and movement abilities of White Zetsu.
This task is both difficult and challenging. After several days of research, he found little progress.
There are sealing techniques similar to what he needs, but they are not fast enough. They are generally used after subduing an enemy to ensure they cannot recover chakra to escape or counterattack. In the ninja world, there is no existing sealing technique that can instantly block all chakra of an enemy.
If such a technique existed, it would be more powerful than almost all other jutsus.
One day, while having a meal with Kakashi, he casually mentioned this idea. To his surprise, Kakashi gave an unexpected reply.
"Are you talking about the interrogation unit's shackles?"
Aoba realized he had made an experiential mistake.
Previously, he had been developing sealing techniques for life force from scratch. When it came to sealing chakra, he instinctively thought it should be done the same way.
But he forgot that this is a world of chakra. There are countless sealing techniques for chakra. While directly using these techniques might not be practical, they can be used in conjunction with tools.
The interrogation unit has several such special devices. Once a prisoner is shackled, even the most powerful enemy cannot use a bit of chakra. They can even cause the person to become completely paralyzed. These tools are specifically designed for ninjas.
In combat, these tools are generally ineffective because real combat involves people. The time you use shackles is often enough to stab your opponent three times. Plus, the design isn't suitable for combat.
However, Aoba was dealing with White Zetsu, creatures that are extremely difficult to kill. They are the type that requires binding techniques to control.
"Kakashi, are you familiar with Ibiki?"
"Somewhat. We interacted frequently when I was in the ANBU."
"Could you do me a favor and borrow a set of shackles from the interrogation unit for me to study?"
The tools used by the interrogation unit employ sealing techniques that are not included in Orochimaru's data. It's likely that Orochimaru didn't anticipate such a peculiar request from Aoba.
While it would be possible to derive similar techniques from Orochimaru's data, having ready-made tools is more efficient. There is too much to study, and time is limited.
"What do you need them for?"
"I'm currently researching a special type of kunai that, when it hits, can limit the enemy's chakra."
"Limiting chakra is clearly a difficult and thankless task. If you want to increase the killing power of your kunai, you could simply apply poison. The Yūhi clan sells such toxins, or you could extract some snake venom from the forest."
"..." Discussing such matters with an expert is quite troublesome. It's hard to mislead them.
Aoba sighed in frustration.
"Actually, it's for a very special research project. Very special."
Kakashi understood that this was something not suitable for public discussion. He didn't press further. The interrogation unit's shackles were indeed a complicated issue.
They were made from special chakra metal, making them expensive and limited in quantity.
On the other hand, the interrogation unit doesn't pay much attention to the quantity because these tools are only used for very high-value prisoners. Normally, regular methods are sufficient to incapacitate a ninja, making these expensive tools unnecessary.
After some consideration, Kakashi said:
"Aoba, I can help you with this. I won't ask for the reasons, but I need you to promise me that your research won't harm Konoha."
Aoba didn't answer immediately but instead asked:
"Kakashi, why would you think I would harm Konoha? I have never done anything against Konoha."
"But you see, Aoba, I can tell you harbor resentment towards Konoha for marginalizing you back then. No, it's not just resentment; you actually hate them."
Aoba realized that Kakashi not only understood him well but had also seen through his hidden emotions. He had thought he was hiding his feelings well, but Kakashi, one of his few friends in Konoha, had seen through some of his concealed thoughts.
Though Kakashi's interpretation wasn't entirely accurate—he didn't hate the higher-ups in Konoha but rather disliked them, with his marginalization being somewhat deliberate. Nonetheless, his disdain for the higher-ups was genuine.
Kakashi had interpreted this hidden emotion as a hatred towards Konoha.
"I must say, Kakashi, your cold exterior often hides a meticulous inner self. But before answering that question, I need to ask you one."
"...Alright, ask away."
"Very well, Kakashi. Tell me, what is Konoha?"
Having asked his question, Aoba didn't wait for Kakashi's response but stood up, paid the bill, and left.
"Think about it, and then answer me."