Chapter 4: An Actual Disciple

Tanjiro watched as the man, who called himself Flashy Flash, jumped from his spot on the tree and quietly landed in front of the boy with a grace that matched that of a bird.

Now that the new arrival had gotten closer, Tanjiro realized that the man was only slightly taller than he was. However, with the overwhelming confidence oozing from him, he appeared taller.

After taking a moment to register what was just said, he decided to respond to the blonde's statement. "I won't ask any questions about you wanting to train me, but please forgive me for being confused about who you are. After all, we just met." His tone was as polite as he could to avoid offending the man in any way.

Flash glared at him, then sighed. "Fine, I'll give you a rundown. But while I do, it is your job to attack me. So that we can gauge your current level."

"Understood!" Tanjiro held his sword up as he prepared to enter a sword fight with the man. His training with Sabito and Makomo will help him here.

The blonde unsheathed his sword from his sheath, but rather than use two hands, he held it in his right hand. He, too, positioned himself for combat.

"I just need to knick him. This is only a sparring match." Tanjiro thought. He quickly did a horizontal slash. "Water Breathing: First Form. Water Surface Slash!"

One moment, Flash was there, Watching as the blade swung for his shoulder. The next, he was gone.

Once Tanjiro recovered from his sword slash, he whipped his head around to look for his opponent. His mind was racing. "Where did he go?"

"I was raised in a ninja village when I was five. Sold by my parents to become a means of profit for my new supervisors." Flash spoke while on the branch of the tree, he was on earlier. Tanjiro raised over his head and performed an overhead slash.

"Second Form: Water Wheel!" Instead of stopping the overhead swing, he performed a front flip that allowed him to follow the flow of the attack that propelled him upwards. Once his body had done a full circle, he had the ninja at sword length before him.

Flash casually evaded a vertical slash from Tanjiro, then jumped between trees to keep him suspended in the air. The younger swordsman began to give chase by jumping between branches, but the fluidity of his movements paled to the ninjas.

"I eventually honed my skills enough to fight out of the village and obtain a new life as a hero. It has become my main priority to hunt down Muzan Kibutsuji. A major threat to humanity." Flash landed on the side of a tree and looked toward his pursuer.

When Tanjiro finally caught up, he jumped forwards and clashed swords with his opponent to try to push him off the tree. "It sounds like a lot is missing from your story. Like, why do you want to train me?"

The hero put his weight behind his sword and shoved the boy towards the Earth, where he landed on his back. "Three reasons. One: I have no way to track the demon efficiently. You have a gift that could allow me to do that, and you already know what he smells like from your experience with him."

Flash pressed his feet against the tree before it shattered beneath him as he jumped towards Tanjiro.

The younger swordsman got up and took a deep breath. "Now is my chance. While he is in the air."

Tanjiro felt a current of power through his body as he used a new water-breathing form. One that, if it connects, will drastically reduce Flash's speed.

"Water Breathing: Seventh form!" He trusted his sword forward. The intention of piercing the ninja's shoulder. "Drop Ripple Thrust!"

The blade sunk into the intended target…

…before Flash disappeared entirely, and Tanjiro felt his legs swept from beneath him.

The red-haired boy blinked as he looked up at the blonde who stood above him. The tip of a sword pressed against his chest. "How?"

"You are not only slow, but you hesitated to attack me with that thrust." Flash pointed out. "In fact, all of your attacks had hesitation in them."

Flash lifted his foot off the boy and sheathed the sword. "I can tell what kind of person someone is when you fight them. You are a kind boy who can be pushed to violence if needed."

Tanjiro slowly rose to his feet. "You came to that conclusion after fighting for only a minute?"

"Both as a swordsman and for any objective, it is considered a necessary trait to process information quickly AND efficiently. Remember that." The ninja began walking to a nearby tree and sat at its base.

"Take no offense, Flash-san, but for someone who claims to want to teach me, you haven't told me anything I don't already know, with some minor exceptions," Tanjiro stated.

Flash shrugged. "It is the first time we have officially met. This was more of an introduction, if anything. I introduced myself, and you showed me who you were through your sword."

The red-haired boy raised his hand abruptly. "But what if I have more questions about you?"

"Then follow me with no complaint, and learn them yourself." The ninja responded roughly. "You wanted to kill Muzan, yes. And to save your sister. Neither of these will be easy tasks. And sometimes, you must choose the path that is the most efficient. You can work with these swordsmen across the continent and become as strong as they are. Or, you get taught by me and not run the risk of dying like a large portion of the others who attempted the exact path you were on before I got here."

Flash continued. "I told you there would be no objections to me becoming your master because it is the only way you will survive. And more importantly to you, to make sure Nezuko becomes human."

Tanjiro's eyes dipped toward the ground. "I am aware my chances are slim. But even so, how would having you as a mentor differ from Urokodaki or other demon slayers?"

The ninja's eyes twitched. He had an answer for the kid. But with everything that had happened recently, how could he say it with confidence? Saitama, Blast, Platinum Sperm, Garou…

That man.

The memories of Flash failing to understand the techniques in the scrolls flashed through his mind when he had spent days trying to understand how basic moves lead up to advanced moves. The same basics he had practiced all his life. It was humiliating.

But the reason he chose to be here was to become the greatest ninja of all time. So even if it meant lying to the kid, it would only be temporary.

"Because I am the strongest. With no rival."

"Well, "Mr. Strongest," sit there while I show Kamado how much he has to learn."

Flash bolted up from his sitting position and took a fighting stance. The newcomer who had just spoken wore a white fox mask with a scar on its head's right side. He also possessed long peach hair and wore a green kimono checkered with yellow. A white robe also surrounded him.

"Sabito, there you are. I was getting worried." Tanjiro spoke up with no concern. All while the normally calm ninja was sweating bullets.

"I didn't sense him." Flash thought. "No noise, no instinct, not even a gust. Who is this guy?"

Sabito started moving forward until he had passed the hero and stood before Tanjiro. "Raise your sword. We have done this many times before."

"Yes!" The red-haired boy readied his sword for combat. Sabito reached under his robe and unsheathed a sword that had been out of sight.

Then, without warning, the mysterious boy started engaging in combat with Tanjiro. Flash put a hand on his sword hilt but relaxed when he sensed neither fighter fully intended to kill the other.

For whatever reason, once Sabito had made himself known, the ninja could detect him like he usually would. Perhaps it was because he was no longer hiding himself.

"Sabito is another student of Urokodaki. As am I."

A cold chill went down Flash's spine, and he turned to see a girl with dull eyes looking at the fight beside him. Similarly to Sabito, she had no presence until she was next to him.

She wore a red yukata with pink and white flower dots. Over this was a sleeveless purple haori. A fox mask similar to Sabito's was placed on the top left side of her head with two blue flowers on the left side of its head.

"And who are you," asked Flash.

"Makomo." She continued to watch the fight with no further comment. The ninja waved a hand in front of her to get her attention, yet she still looked on with bland eyes that could see souls.

This girl was creeping him out.

…

Flash continued to watch the two younger swordsmen spar from his place below a tree. All while reading the scroll filled with complex techniques that had been looted from "That Man."

He finally understood the relationship between the three children present.

Makomo would give Tanjiro tips on how to perfect the water forms. It could be to move more like a river or when to breathe in during the attacks.

Sabito put these moves into practice. His sparring with Tanjiro forced the red-haired boy to adapt them to his fighting style. Practice makes perfect. Or so they say.

The peach-haired boy knocked Tanjiro to the ground one last time. "That's enough for now. We'll try again later."

Flash closed his scroll and stood up. "Then it is my turn to train Kamado." He began making his way toward his student.

The scar-faced boy stood between them. Sword raised to confront the ninja. "Now, hold on. First, you must prove you are capable of teaching Tanjiro. Fight me! Flashy Fla…"

A sound of metal could be heard throughout the forest. Sabito blinked before he realized that the sword in his hand was missing most of its blade. He turned left to see the other half of his sword was embedded in a nearby tree.

Tanjiro watched wide-eyed. "When did he draw his sword? When did he SHEATH his sword."

The ninja, who had not broken stride, or shown he had used his sword, walked past Sabito. "Kamado, follow me."

…

The small group eventually approached an overhead cliff about 20 meters tall. Flash began nodding to himself. "This will do."

Tanjiro tilted his head in confusion before an explosion of dust occurred next to him, which forced him to shield his eyes.

Once the air cleared, the ninja was nowhere to be seen until a yell came from above. "This is your first time training with me, Kamado, so listen closely!"

At the top of the cliff, Flash stood next to a large pile of small rocks. "In order for me to teach you how to move at high speed, you will need to increase your reaction speed greatly."

The student yelled up to the hero. "Wouldn't that increase through combat with practice!?"

"Yes, but not as quickly as this method. You see, we don't have a way for you to fight many opponents at the same speed the way I was trained. But many of the younger people had ways to exercise that they used for entertainment."

It took Tanjiro a moment to understand what he meant. "Games? Like Janken?"

"If you confuse this for a game, you will lose." He held up a small rock. "Cut this pebble."

Flash dropped the rock from the top of the cliff. Once it was in sword range, the red-haired boy unsheathed his sword and sliced the stone in two.

Then immediately got hit in the face by the separate parts.

"You must also still dodge the attacks as well! Your katana will not shield you after the cut like other swords! It is too fragile for that! This training will force you to dodge attacks as well as intercept them at once!"

Tanjiro shook his head and took a determined stance. "I understand, Flash-san!"

More rocks began falling from above. "Sensei!" The ninja corrected.

The student began slashing the rocks out of the sky. Flash would chastise him when he missed one or got hit by yelling out how many times he had messed up this session. That didn't drain Tanjiro's determination, however.

This training occurred to the ninja because of the time Atomic Samurai had challenged him to combat.

(Months earlier.)

"Flashy Flash."

The ninja, who had just left an annual S-Class meeting, turned to see the rank four hero, Atomic Samurai, approach him. His three students flanking him.

"What is it? I'm a busy man." Started the ninja.

"Surely you have never been curious about which of us is stronger. I myself wonder if your insane travel speed could compete with my unmatched combat speed and skill." The older hero stated.

"I have not. There is nothing to be curious about. You wouldn't even know the fight had started because it didn't."

The three A-Class disciples swallowed. Iaian took a step forward. "Flash-san, please refrain from angering our…"

Atomic held his left hand up to silence his student. A shadow was cast over his eyes. "You truly think so little of me, Flashy Flash."

The ninja gripped his sword hilt. "You are not weak, Samurai. You just don't compare to me."

The older hero glared at Flash. "Let's test that theory. Shall we?"

Both swordsmen drew their swords and lashed at each other.

"Stop!"

The two blades halted, centimeters from each other. Everyone turned to see a sweating Child Emperor raising his hands toward the two. "Don't kill each other! You are both S-Class heroes!"

They looked at each other and sighed before dropping their blades. "We had no intention of killing each other."

"Really?"

"No," said Flash.

"Yes," said Atomic.

Atomic glared at Flash and vice versa. "You are a terrible liar!

"Of course, that's why everything I've said today has been the absolute truth. Including how I outmatch you."

"Enough!" Child Emperor snapped. "Are all adults this stubborn? Holy Cow! Just follow me."

…

"What?" Both S-Class swordsmen stared dumbfounded at the two machines next to the genius child.

"Two Galaga machines set to speeds beyond the normal eye could see. Whoever gets the higher score will be declared as the better swordsman for combat.

Atomic walked up to the machine on the right. "Is this necessary? How will this prove the better swordsman for combat?"

Child Emperor pointed to Atomic. "You may be fast, but your precision in combat excels Flashy Flash's. This will show when you have to react to incoming threats on short notice."

The boy's finger moved to the left machine where Flash was messing with the joystick. "You have a much faster top speed than Atomic Samurai. This will show when you have more time to react to incoming threats."

He pointed to both of them. "This will show who's trait is better for combat without the risk of combat. Precision vs Speed."

Flash and Atomic looked at each other and then back to the machine.

"We will do this one time to settle things. But don't expect this stunt to work a second time, boy." Atomic said.

The three students of the samurai breathed a sigh of relief before Child Emperor started the countdown to the match.

"3, 2, 1, Go!"

…

(Present Day. Or the past, depending on how you view it.)

Flash remembered the two of them spending hours facing off until both screens went haywire and glitched the score. They had been so tired by the end because the advanced arcade machine had stressed their reaction time the entire time.

They were so exhausted that they hadn't even decided to settle the match with a sword fight as they went their separate ways.

Tanjiro's current training was similar to the game but much more stressful considering the attacks weren't virtual.

…

"That's enough for today."

Flash looked down from his spot on the cliff. Tanjiro kneeled over, panting from his extended training session. The hero dropped down next to the boy.

Then he looked around and thought to himself. "Where did the other two go? They so easily get out of my sight. Are my senses weakening?"

He then shrugged and looked back at his student. "You made 561 mistakes. 102 dodge fails, and 459 missed rocks." Flash reached for his water flask and gave it to Tanjiro. "Always keep water on you. A metal flask is most effective due to the off chance that an opponent hits it instead of you."

"How did I do?"

"Slightly better than I expected."

Tanjiro took a small drink out of the canteen and tried to hand it back to the ninja, who declined it. "While I am keeping track of your performance during this exercise, its main purpose is to improve your reaction speed. It doesn't need to be said that the more you repeat it, the better you get."

"Is this similar to your training, Flash-san?" Tanjiro stood straight and looked at Flash.

"It's Sensei. And as I stated before, my training involved multiple swordsmen attacking each other endlessly. It forced us to take combat seriously because if we didn't, we would face a fatal injury."

The ninja raised a part of his shirt to reveal a puncture scar close to his stomach. "This wound nearly killed me when I was six. After that, all my training was completed with all my effort."

Tanjiro watched as he put the shirt back down. "Six is a young age for someone to be training to kill."

"You think the people in charge of us cared? Demons aren't the only ones who can be cruel. Humanity has its fair share of evil. Everyone has some in them. Even you and me."

The boy took a step forward as his brow furrowed. "I believe it's the opposite. All creatures have compassion in them. But the more you lose, the more cruelty takes place. But a person could never lose all their compassion."

"Would you include Muzan as someone who has compassion?"

Tanjiro flinched and then looked toward the ground. Flash nodded and turned to walk to where the clearing that had the boulder was located.

But he stopped when Tanjiro spoke up again. He looked back at the younger swordsman.

"Yes. As much as I hate him. As much as I like to stop him. It can't be denied that he does possess compassion deep within him."

Flash scoffed.

"But…"

Tanjiro lifted his head to look right back into the hero's eyes. "That doesn't mean he should not be stopped. I will stop Kibutsuji, not because I hate him. But because it must be done. Because if the compassion inside someone does not outweigh their cruelty by a hundred times, then there's no other reason for the kind to stand in their way."

They glared at each other for a moment. The wind blew through their long hair as the tension reached its highest between the two.

But eventually, Flash closed his eyes and continued down the path to where they would rest. "It is getting late. You should prepare to sleep."

Tanjiro let out a breath he had been holding and started to run to catch up to the ninja, who was smiling to himself.

"Perhaps I underestimated you." Flash thought. "It was my impression that you were too kind for your own good. But that kindness should not be confused as mercy."

The ninja looked towards where the sun was starting to make its descent over the horizon. The red sky became black as night fell upon them.

"Continue to impress me, Kamado. If you do, your future might not be so bleak."

After this thought, Flash disappeared as he sprinted into the distance.

…

(Author's Note)

I decided to use "..." as a way to distinguish jumps in the story because when I used a horizontal slash, it would not show up in AO3. Also, instead of writing thoughts in Italics, they will be stated as thoughts in the paragraph or close to it. This is because I couldn't get Italics to work on AO3 either.

I hope you enjoyed this chapter as much as me. Thank you for your support.