Naruto: Chakra System

Naruto mused, "Wind, huh! Then, Kakashi-sensei, are you going to teach me Wind Nature B-rank Ninjutsu?"

Kakashi nodded and said, "And for you, Sasuke, I will teach you a Lightning Release B-rank Ninjutsu, since you already have Fire Release, so teaching you another Fire Release is not needed."

Sasuke nodded in understanding, and Sakura thought and asked, "Kakashi-sensei, are you going to teach me a Ninjutsu too, or just medical ninjutsu is enough for me?"

Kakashi replied, "Yes, I will also teach you a few Earth and Water nature Ninjutsu, but not now, in the future when you have enough chakra and strength. For now, you will be mostly focusing on Medical Ninjutsu from tomorrow onwards."

Sakura nodded. Then Kakashi considered and said, "Oh, and Sakura, I will teach you defensive Earth Release Jutsu. With Medical Ninjutsu and Defensive Ninjutsu, you will become a pillar of Team 7 in the future."

Sakura's eyes sparkled, and with joy in her voice, she said, "Thanks, Kakashi-sensei!" She was really happy that she might be a real help to Sasuke and not a burden.

Naruto asked, "But Kakashi-sensei, is Wind Release stronger than Fire and Lightning Release?"

Kakashi raised his brow and thought, 'Huh, he's still competitive with Sasuke in this case as well.'

Sasuke also showed a competitive glint in his eyes when Naruto asked this, and looked at Kakashi to know which nature element was stronger, his or Naruto's.

Kakashi explained, "Well, in reality, no one can be said to be stronger than any. It usually depends on the user, but there are elemental advantages each nature transformation has. Fire Release is strong against Wind, but weak against Water; Wind Release is stronger than Lightning but weaker than Fire; Lightning Release is stronger than Earth but weak against Wind; Earth Release is stronger than Water but weaker than Lightning; and lastly, Water Release is stronger than Fire but weak against Earth."

Hearing a complete explanation, Naruto, Sasuke, and Sakura nodded in understanding. While Naruto and Sasuke had a competitive glint in their eyes, neither said anything, because both had one win and loss against each element they possessed.

Sakura then asked, "Sensei, what nature affinity do you have?"

Kakashi answered, "I can actually use all elemental affinities Ninjutsu, but my innate chakra nature affinity is Lightning."

Naruto, hearing this, asked, "Hm, can anyone use other nature transformation Ninjutsu as well, aside from their primary affinity?"

Kakashi nodded and said, "Well, technically, yes, but learning other nature transformation Ninjutsu aside from a ninja's own innate affinity is very, very hard, and for many, properly using any new affinity ninjutsu's takes even several years."

The three Genin were surprised, and Naruto asked, "If that's the case, then how can you use all of them?"

Kakashi chuckled and replied, "Because I can copy Ninjutsu, and other elemental Ninjutsu I can use are mostly copied. And after the Sandaime-sama, I am the only known Ninja to ever be able to use all nature transformation Jutsu."

The three of them were shocked once again, and this time Sakura asked, "Does Sandaime Hokage-sama also can use all nature transformation Jutsu?"

Sasuke also immediately asked, "What do you mean by copied Jutsu? How can you copy Ninjutsu? Tell me!"

Naruto also asked, "Kakashi-sensei, can I also copy Ninjutsu as well? Teach me, Sensei, teach me that trick too!"

Kakashi, hearing all these barrages of questions, sighed and chuckled and replied, "Well, for your answer, Sakura, Sandaime-sama is also known as 'the Professor' for the same reason, because he was talented enough to learn all nature transformations. Maybe he inherently has affinities for all nature transformations."

Kakashi then glanced at Sasuke and Naruto and asked, "Do you want to know a secret, Sasuke? Have any of you three ever thought why I always cover my left eye?"

Kakashi's question made all the Genin curious, especially Sasuke. He had, for some reason, an odd feeling about Kakashi's reason for covering his left eye.

Naruto said, "Well, I actually thought about it once, but then I concluded that you're a Jōnin and have done many missions, so you might have lost this eye in some battle."

Kakashi was surprised and jokingly asked, "Naruto, you can also think? That's really surprising!"

Naruto chuckled embarrassingly; he couldn't tell if Kakashi had praised him or insulted him. He then asked, "Then is my guess correct?"

Kakashi shook his head and replied, "No, that's not the exact reason; you're just half correct!"

Sasuke couldn't control his bubbling curiosity and the strange, odd feeling about it and asked, "Then what's the reason behind you covering your left eye?"

Kakashi grinned under his mask and said, "Naruto, you're correct about me losing my left eye in battle. I lost it in the Third Great Shinobi War, but the real reason I covered my left eye is because..."

He paused, looked at Sasuke and the other two's anticipated expressions, and continued, "My left eye is now actually a transplanted Sharingan of the Uchiha Clan, your clan's Dōjutsu, Sasuke."