Naruto: Chakra System

After 15 minutes of contemplation, Kakashi decided to train in Fūinjutsu first and also training in merging Rasengan with Fire Release. Although he wasn't very motivated to train all this by himself, so he decided to use his Shadow Clones to do most of the work.

The choice of Fire Release for merging with Rasengan came from deep and reasonable thinking. He understood how unstable Rasenshuriken was, so that was out of the question for now, but he would try it in the future.

That left the other four elemental Nature Transformations—Earth, Water, Fire, and Lightning. Lightning Release was his main affinity, but he understood that Lightning Release would also be as difficult and unstable as Wind Release to merge.

Not to mention, he knew that Chidori, and its refined version, Raikiri, were actually created from his failed attempts to apply Nature Transformation to the Rasengan, which led to a new, distinct technique. So, Kakashi knew that Lightning Release Chakra was also difficult to merge with Rasengan, even if not impossible.

Water Release would perhaps be less impactful if merged with Rasengan, so that was also out.

Then, this left Earth Release and Fire Release. Both could create a different and powerful variant of Rasengan and were much easier in the merging process than Wind Release and Lightning Release, though still difficult in process to merge with Rasengan.

Kakashi thought that Earth Release would likely create a dense, incredibly heavy, rock-hard sphere. It might add crushing impact-amplifying properties, possibly leading to a small, cracked meteor-type Rasengan.

And with Fire Release, it might create an intensely burning, swirling orb, another Rasengan variant. It might add incineration, explosive force, and widespread burning capabilities.

Both Fire Release and Earth Release had high chances of being more stable during the merging process than Lightning Release and Wind Release, which were unstable even when created, as Rasenshuriken was unstable and highly dangerous even to the user unless used with Sage Mode Transformation.

And more than a rock-hard, cracked Rasengan, a burning, swirling Rasengan sounded more appealing to Kakashi, so he chose to merge Fire Release with Rasengan. With this decision, he made a hand sign, creating 20 Shadow Clones, and sent them to a training ground to start practicing with the Rasengan, training to applying it with Fire Release chakra.

He himself went to Ichiraku Ramen shop to have lunch, as it was only afternoon. Tomorrow he had to meet with Team 7, so he decided to ask Hiruzen Sarutobi for the Four-Symbol Seal the day after tomorrow.

—

The Next Day!

Early in the morning, Kakashi woke up, took a cold shower, had a healthy breakfast, and got ready to go and meet his student Genins. After wearing his usual Jōnin attire, face mask, and with his left eye covered under his forehead protector, he summoned his status panel before moving.

[Host: Kakashi Hatake]

[Chakra Pool: 284,320/285,990]

[Chakra Control: 89/100]

[Chakra Level: Elite Jōnin]

[Chakra Affinity: All]

[Chakra Growth: +20,000 per day]

Kakashi looked at his stats and couldn't help but commented, "Huh, it's still Elite Jōnin in Level?"

But then his focus went to his Chakra Pool, and he noticed, "Yesterday it was 265,260 in total, and today, aside from the system's extra 20,000 points, my own increased by 730. Hmm, maybe it's because of having Shadow Clones train in the Rasengan merging with Fire Release Chakra."

Though it was very little compared to his total chakra, he felt a strange sense of accomplishment at having increased his chakra reserves by himself, even if the numbers were seen quite small.

He stated, "But this also helps me understand that at one point, chakra reserves grow at a very slow pace and literally stops. Training the Rasengan, merging it with an elemental nature, can itself be considered an S-rank training program. And my chakra only increased by 730. This means with other standard training, I will see no improvement at all."

He then shrugged, letting go of these thoughts, and left his house, closed the door behind him, and flickered outside with Body Flicker.

—

It was only 8 AM currently, and the sun was shining brightly on the village, hidden in the leafs, Konohagakure.

Upon arriving at Training Ground 3, he saw all three Genin were present, in their same usual attire as yesterday. Sakura stood on the left, Naruto in the center, and Sasuke, crossing his arms, on the right.

All of them were visibly nervous. Sakura and Naruto's faces clearly showed it, and despite Sasuke's aloof expressions, he was fidgeting his fingers, constantly glancing around.

They all carried small bags, which held their weapons and tools, which surprised Kakashi. He thought, 'Why didn't they just put them in their ninja pouches alone?'

But he dismissed this thought and came in front of them. "Hey kids, good morning!" he said.

Sasuke nodded slightly, Naruto crossed his arms and huffed, and Sakura meekly and in a low voice said, "G-good morning, Kakashi Sensei."

Kakashi then nodded. "I hope you all are prepared, so shall we start our test?"

Naruto yelled, trying to cover his nervousness, "Yeah, I'm ready! Let's begin your test, I will definitely pass and become a ninja!"

Kakashi once again glanced at the three of them, took out one bell from his pocket, and showed it to them. He started to explain the test, "Your task is..."