Naruto: I start with one door, and I can open it infinitely.

"How is this possible?" Uchiha Sasuke stared at the kunai with ten bullseyes. He couldn't even do it, so who was this person? How could they possibly do it?

In the past, he wouldn't have even been interested in knowing the other person's name. But now, the name Chiba Rinkawa is deeply etched in his mind, making him remember the man who defeated him.

"Who is this person? I've never heard of him before." Sakura Haruno looked at Lin Chuan's somewhat unfamiliar face. She usually only paid attention to Sasuke and hadn't paid attention to anyone else. She really didn't know that there was such a person in their class.

"I think I remember him, the one who got into a fight with Choji and the others right after the start of the semester, right?" Ino said uncertainly. She was more familiar with the other two members of the Ino-Shika-Cho trio and had only heard them mention Rinkawa before.

"Wow, Lin Chuan, you're amazing! How did you do that? Can you teach me?" Naruto leaned close to Lin Chuan, genuinely eager to learn from his incredible performance.

"Haven't you seen it before? Throw kunai three hundred times a day, and you'll be fine after three years," Lin Chuan put the kunai spinning in his fingertips back into his ninja tool bag. He didn't notice Naruto and the other two following him the first time, but they followed him too many times, and he eventually found out.

"Huh? Three years? Three hundred times a day?" Naruto was completely dumbfounded when he heard this amount of training. Was this something a human could do?

It's too difficult; he can't do it!

"Naruto..." Hinata hid in a corner of the crowd, quietly watching the frantic Naruto with her Byakugan. She believed that Naruto would definitely pass the test next time.

"The exam is over. There's another kunai throwing test next month," Iruka warned, looking at the students who failed, especially Naruto who only got one point. "Anyone who fails the next exam will have to clean the toilets for a week..."

"No way, cleaning toilets?" Naruto was even more distraught when he heard that he had to clean toilets. He had to learn how to throw kunai before the exam next month, at least to pass.

Everyone avoided Naruto's pleading gaze. Shikamaru, who found it troublesome, didn't even bother to look at Naruto and went straight back to the classroom; they were about to finish school.

"Naruto, didn't you see my training? Just follow my training instructions," Lin Chuan said with a smile as he left. As long as Naruto was willing to train hard, he could still master throwing kunai, since throwing doesn't require chakra.

"Lin Chuan, can I train with you?" Naruto quickly caught up with Lin Chuan, not expecting his lunchbox friend to be so strong, having already defeated Sasuke.

"Okay," Lin Chuan nodded lightly, picked up his schoolbag and lunchbox, and prepared to go home. Little did he know that his performance today had earned him a good scolding from someone.

When Sasuke got home from school, he saw his older brother Itachi about to leave. He immediately ran up to him, hugged him, and begged, "Brother, practice kunai with me!"

"Next time, Sasuke, I have a mission," Itachi said with a smile, refusing Sasuke's offer. He even tapped Sasuke's forehead lightly. By this time, Itachi had joined the Anbu, so his missions were naturally Anbu missions as well.

"Oh, really?" Sasuke was a little down because he had lost the exam today and heard that Itachi was going on a mission.

"What's wrong? What happened today?" Itachi gently poked Sasuke's forehead with his finger. He noticed that Sasuke's mood was off. Sasuke wasn't usually like this; at most, he would feel a little regretful. Today, he seemed unhappy.

"It's nothing, the school had a kunai throwing test today," Sasuke said, too embarrassed to admit that he only got second place.

"A kunai throwing test? What place did you get, Sasuke?" Fugaku Uchiha had just arrived at the entrance when he heard about the kunai throwing test. Seeing Sasuke's unhappy expression, he knew it couldn't be anything good.

Faced with his stern father, Sasuke dared not hide anything and could only lower his head, whispering, "Second..."

"Who came in first?" Fugaku Uchiha was genuinely curious. Among a group of children who had just entered school, was there anyone with a stricter education than his family? Even Sasuke only came in second.

"It was someone named Chiba Rinkawa," Sasuke said, lowering his head even further. He had never heard of this person before and had actually been defeated by him.

"Chiba? Hah," Fugaku Uchiha pondered for a moment, then suddenly snorted coldly. He realized it was a surname he had never heard of before, and it didn't even belong to a minor ninja clan. He guessed it was just an ordinary ninja from Konoha.

Unexpectedly, Sasuke lost to an ordinary ninja's child. His face darkened as he looked at Sasuke and said in a deep voice, "Sasuke, I'm very disappointed in you. Go to the backyard and practice throwing kunai a thousand times..."

"Yes, Father. There's a kunai throwing test next month. I'm sure I'll get first place," Sasuke said, head down, too ashamed to look at his brother, and headed straight for the backyard.

"Father, I have a tight mission here, so I'll be going now." Itachi held the Anbu mask and saw Sasuke walk away with his head down. He wanted to say something, but his father was too stern, so he didn't say anything in the end.

"Alright, go ahead. The mission is important." Fugaku Uchiha nodded gently, watching his eldest son leave. He sighed helplessly. The relationship between the Uchiha clan and the village was getting worse and worse, and he found himself powerless to do anything about it.

The information about Chiba Rinkawa was quickly delivered to him. Upon seeing Chiba Rinkawa's information, it was indeed as he had thought: the child of an ordinary ninja, whose father was only a Chunin.

"Another genius?" Fugaku Uchiha muttered to himself, putting down the documents in his hand. So what if he's a genius? Konoha has never lacked geniuses. It's just that the Uchiha clan is no longer able to pay attention to these things. Sigh...

……

After returning home, Lin Chuan ate dinner and then went to the backyard to start a weighted jog. After jogging, he went to the river to practice ninjutsu. After a week of learning, he successfully mastered the hand seal sequence of Water Clone and Water Chaos Wave, and even released a water-style ninjutsu once or twice.

With only one hand seal for his water clone, coupled with the dense water vapor by the river and his high affinity for water attributes, he quickly mastered the transformations of water attribute chakra.

My cheap dad is right. Learning attribute transformation from the chakra attribute that's compatible with his own makes practicing ninjutsu much more efficient and saves him a lot of learning time. If he could use shadow clones to speed things up, he might be able to learn even faster!

Next, he needs to master the hand seals for the Water Clone Technique and the three hand seals for the Water Chaos Wave Technique: Chen, Chou, and Mao. As long as he can release the ninjutsu, he will be considered qualified, and instantaneous release is considered mastery.

In addition, with precise chakra control and the damp environment by the river, he could completely use the river water to condense a water clone. He felt that without the river water, he could only use the water clone once with the amount of chakra required for a C-rank ninjutsu. With the river water, he could use the water clone three times with the same amount of chakra.

The influence of environmental factors on ninjutsu is not to be underestimated. In the presence of water, Water Wave cannot be used and can only be released twice because Water Wave is spat out from the mouth.

If it were a dry environment like a desert, he felt that he would need to add half again as much chakra to release a single water wave, and the amount of water would be pitifully small.

"Water Release: Water Chaos Waves," Lin Chuan slowly completed the three hand seals, then opened his mouth and sprayed a stream of water towards the trees by the river, which struck the tree trunks and made a banging sound.

After the water stopped churning, he noticed that the tree trunk had only trembled slightly from the impact of the water flow, shedding some leaves and bark, before quickly stabilizing.

It's not that the water flow isn't strong, it's just that the water ripples he creates aren't strong enough. He needs to practice more to shorten the release speed while increasing the impact force of the water flow.

Using the breaking of this large tree as a benchmark, he gazed at the tree that had just been battered by the water flow; his next sparring partner was yet to come…