"Huff huff huff"

Deep breathing sounds were heard in the basement. A 15-year-old youngster was on his knees, his hand resting against a pillar. His body was covered in sweat. His chakra was exhausted. It looked like he was barely hanging on. However, contrary to his physical state, a wide smile could be seen on his face despite the fact that he was breathing heavily. Suddenly, the smile grew wider and the youngster began laughing in an unbridled manner!

"Hahahaha hahahaha!"

The sound of deep breathing was replaced by continuous laughter. Fortunately, the basement was sealed. If he was outside, people would wonder if he had some issues.

Finally, the youngster took his hand off the pillar and sat with his back resting against the pillar. He constantly switched between laughter and breathing heavily. The spot from where the youngster removed his hand had a small mark.

Fujin took a few minutes to catch his breath. However, the smile was plastered on his face. He thought, 'I did it! I'm the 3rd person in Konoha and perhaps in the history of this world to master the Flying Thunder God jutsu!'

He continued taking deep breaths while thinking, 'This damn jutsu! For so long I felt like I was close to learning it. It still took me 3 months to finally master it! Also, how insane was that pressure? It sapped all my chakra when I tried resisting it! Though my clones also experienced that pressure, it was far more intense for me! Why is it so?'

Fujin couldn't be sure. He could only guess, 'Is it because my chakra is far greater than my clones? Hmm, I doubt it. Even when my chakra decreased, the pressure didn't decrease. Besides, the clones that tried entering the Void Dimension didn't necessarily have the same chakra.

If not chakra level, could it be because I'm a being made of flesh and blood instead of a chakra construct?'

Fujin felt that this was the case. Unfortunately, the scroll Hiruzen provided didn't have any information regarding this matter to verify his speculations.

Fujin thought, 'After I enter the Void Dimension, I have to resist the pressure while locating the mark I want and creating a connection with that mark. Both of them take a lot of chakra. Moving through the dimension takes some chakra as well, though it isn't much.

From what Tobirama wrote, the amount of chakra I consume will reduce once I get used to the pressure. If I can locate the mark and teleport in an instant, then I won't have to resist any pressure. Only at that stage, this jutsu can be freely used in battle with very little chakra expenditure.

Fortunately, it isn't very difficult. I'll just need to practice it a few tens of thousands of times to reach that stage. Once I do, I'll need to start working on increasing the range I can teleport. For now, I have been only practicing in the basement. My Shadow Clones can freely teleport to any marker in my house.

This distance isn't enough to escape but it is good enough to be a menace on the battlefield. That said, how do I practice teleporting a longer range? I can't practice it in the open. Hiruzen will notice me without the seals.

I can't place seals all around the village to create hiding spots either. Even if I come up with a bullshit excuse, Hiruzen and Danzo will be suspicious and investigate further. Should I openly claim that I have mastered this jutsu?'

Fujin thought for a bit and shook his head. He decided, 'No, I am planning some crazy things to do in the future. I might need the Flying Thunder God then if I need to escape. If it is common knowledge that I know this jutsu, then it'll become very easy to link it to me.

Though I'm not scared, it'll be a huge headache if Akatsuki and enemy Kage begin targeting me openly. If that happens, I'm not sure if Hiruzen or Tsunade would support me if those things come to light. Regardless, such obstructions will slow down my plans considerably. It's best to keep it a secret. If I have to use it, everyone who sees me using it has to die.

But, if I keep it hidden, how do I train it?'

Fujin was in a dilemma. He placed his chin on his hands and thought while he was staring at the ground. Suddenly, he realized, 'Wait a minute! I just need space to teleport. Why does it have to be on land? I have to think in terms of altitude, or rather, depth. I'll just practice underground.

To start with, I'll dig a hole and cover it in seals to prevent anyone from detecting it. I can go as deep as the temperature allows me to. It'll allow me to increase my range considerably.

Once I increase the range to beyond a few hundred meters, I can just go to the wall around the village and teleport my Shadow Clones outside. They can move some distance away from the village and practice longer range teleportations. Hmm, that should do. If I still face any issues, then I can only go to Mount Muteki and practice there.'

Fujin was satisfied with his training plan. However, there was one thing still on his mind that he couldn't get rid of. He thought, 'Why was the pressure on me in the Void Dimension so high? Also, what happens if I can't resist it?

My clones get dispelled once they can't resist it. But they are chakra constructs while I'm a living being. Will I be killed by the pressure? But if there is such a huge risk, why didn't Tobirama or Minato mention it? Also, why didn't they use it to kill their opponents? Can't I just teleport an enemy here and wait for them to die due to the pressure?

If that is the case, there should have been no one who could resist Minato and Tobirama. Even Hashirama and Madara wouldn't survive that. Perhaps only Obito and Kaguya could due to them having access to their own dimensions. However, they couldn't do that. So, what is that I am missing?'

Fujin thought for a long time and thought of several possible answers, but he couldn't be sure of any of them. He decided, 'I'll need to experiment. This is too big of a danger to ignore. Unfortunately, my clones can't help me. I'll need to take a risk to find out the truth! I need to wait until my chakra recovers.'

Fujin had become impatient. He wanted to uncover the truth as soon as he could. He grabbed a small bottle and consumed a pill from it. Sitting with his back against the pillar, Fujin closed his eyes and began meditating.

A couple of hours later, Fujin's chakra had completely recovered. He opened his eyes and thought, 'This might be the most risky act I have done in this world. Probably even more risky than when Roshi fired that Tailed Beast Bomb at me. I hope everything goes well.'

Fujin focused on one of the Flying Thunder God marks in the basement. A moment later, his body disappeared and entered into the Void Dimension. An immense pressure was applied on him and he instinctively used his chakra to defend himself. He muttered, "Here goes nothing."

Suddenly, Fujin stopped using his chakra to defend against the pressure. His chakra reserves were still quite full. His mind was at the highest alert. He was prepared to use the chakra to defend himself once again if his body couldn't bear the pressure.

To Fujin's surprise, as soon as he stopped resisting, his body was expelled out of the Void Dimension and he appeared at the same spot in his basement.

A wry smile appeared on Fujin's face as he thought, 'No wonder they didn't say anything. We just get pushed out if we run out of chakra to resist the pressure. That's quite convenient. Now I see why this method can't be used to kill other nin'

Suddenly, Fujin had another idea. He analyzed, 'Wait, even if I can't send other ninjas to this dimension to kill them, can't I send them here just to exhaust their chakra? After all, any rank S ninja will instinctively resist the pressure. And, in a dimension where they can't see, smell, hear, feel or sense anything, they'll exert themselves to the fullest just to survive.'

Fujin thought for a bit before concluding, 'Yes, this seems practical. The only issue is that this method was never used before either and isn't mentioned in the scroll. Neither Tobirama nor Minato should be stupid enough to overlook such a simple thing. I guess I'll need to find a test subject to experiment on'