Opening: Distortion by BABYMETAL

Tanjiro was taken to Shinobu's household which was called the Butterfly Mansion. It's a large building, comparable to that of the headquarters he was just at. There, he found Inosuke and Zenitsu resting. Apparently, Zenitsu had followed after them when they left him behind and he found his own batch of trouble along the way. Due to their injuries, they were to undergo rehabilitation to get themselves back in shape. This would put the trio out of commission for a little bit as they focused on recovering their strength. However, the first day was spent focusing on their injuries and cleaning them up. The following day would be when rehab began for the boys.

Tanjiro was now resting in bed along with his comrades, each of them asleep because it was late at night. The boy had difficulty sleeping, tossing and turning in bed because of a nightmare he was having. He was seeing it again, the day everything changed for him: the night he had lost his family.

Due to his father being absent, Tanjiro was the man of the house as he had to take care of his numerous siblings. Nezuko was the eldest amongst the siblings besides Tanjiro. He had to sell charcoal they collected to the nearby town to make money so his family could survive. However, he took longer than expected and decided to stay the night at a friends house just to be safe. When he came back home in the morning, he was greeted to the sight of his massacred family. Their corpses strewn across the floor with blood painting the walls. Only Nezuko survived the attack because she had become a demon. He later found out it was by Muzan's hands that his family was taken from him.

That was two, long years ago but the memory haunts him day and night. He could only imagine the screams of his family and his little siblings crying out his name as they were slaughtered one by one. Why? Why did it have to be his family? Why was he the one to meet this untimely fate? He lives with a constant regret eating him up from the inside. He couldn't forgive himself for trying to play it safe and come to his family's aid. Maybe, if he had come sooner, they would still be alive. It's his fault for being so weak and allowing his family to die while he was taking a luxurious nap at someone else's house.

The horrific imagery flashed through his mind and it soon overwhelmed him as his eyes shot open. He stared at the ceiling before his vision became blurry due to the tears welling up. He couldn't hold it in as they rolled down his cheek and stained the pillow he was resting on. Tanjiro silently sobbed as he covered his face. He was just a thirteen year old when his life changed, yet, he was the oldest amongst his siblings. He had to put up a tough facade around everyone because they went to him for help. To everyone, he is a shining example of wisdom and leadership. However, he never has anyone to go to for that same help, no father or father-figure to seek out for wisdom when facing hardships. He's been forced to bear everything on his own for so many years. As a result, he can only let his bottled up emotions release when he's all by himself, as to not discourage anyone else around him.

He has to be strong for Nezuko and the people around him, because they also don't have anywhere to look. However, a fifteen year old can only handle so much. He's still trying to understand the ways of life, attempting to organize his thoughts and feelings at every turn while everyone else expects him to know the answers because they're in the same predicament.

Perhaps, that's why he gravitates towards the Hellwalker so much. The Hellwalker possessed many of the same qualities his father had. They were fearless, strong, and always took initiative, but most importantly: They were caring. Under all that rage within the Hellwalker: there was a caring side that looked out for others. It's because of these traits that Tanjiro became so fond of the Hellwalker. He only knew the man for a day but his actions spoke louder than any word could describe. That's why he was overwhelmed with sheer joy when the Hellwalker defended his sister even though he hates demons with a passion. It was a true act of kindness that the boy would not soon forget.

He heard rustling near him, he turned to see Zenitsu rolling around on his bed while snoring. Tanjiro quickly wiped his tears away and reassured himself that he has to stay strong no matter what. He has to get back to full strength so he can repay the Hellwalker.

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It was early in the morning and both Urokodaki and the Slayer were ready to go. They were outside the shed preparing for that day's training session. Urokodaki had something to explain to the Slayer: "Before we begin teaching you water breathing, we must first go through the basics of breathing. It's something every creature does but they do it incorrectly. They don't utilize their breaths to the fullest and tap into their body's latent potential. The most that people understand about breathing is to take deep breaths whenever you're exhausted or stressed. It's partially the same principle, but there's more to it than just that."

The older man motioned for the Slayer to follow him up the mountain. As they hiked, Urokodaki continued with his explanation, "Everyone has their own unique breathing forms, it's not as simple as simply learning from an individual. If it were that simple, a swordsman can simply learn every form of breathing and call it a day. We each have a limit, not a physical limit: but a spiritual limit. You see, each person's breathing forms are dictated by the person's spirit. For example, swordsmen with a calm and focused heart tend to specialize in water-related breathing techniques; On the other hand, a person who is burning with passion and ambition would be considered for fire-related techniques. Don't get me wrong, it's entirely possible to learn multiple techniques. However, you can only go as far as your spirit allows, and that takes mental and physical discipline."

It didn't take long for them to reach the snowy part of the mountain. As they ascended, the air grew increasingly thin as they marched along and the mountain became steeper. After several, long minutes of hiking: they reached the peak of the mountain. They could see for dozens of miles from where they were at. Sakonji finished his explanation as he informed the Slayer, "However, to be able to do ANY breathing techniques: we must open up our spiritual gate by mastering the basics of breathing. Being atop this mountain has caused the air to be extremely thin. This is overwhelming for the average person, but an experienced Demon Slayer will acclimate to these conditions with ease. These intense conditions will force an individual to confront their spiritual gate and how you open it will dictate what breathing form you will specialize in. I leave the rest to you, Hellwalker."

Urokodaki walked away far enough to be out of plain sight. The Slayer took off his helmet, his warm face being met with the freezing air of the mountain. It was cold and harsh. He can handle it, he's been through worse. Whether it be traversing through the flames of Hell, hopping around the asteroids surrounding Mars, or surviving the freezing cold of Cultist Base, he will make it like he always has..

The Slayer closed his mind off to the world as he shut his eyes. He focused on taking in deep breaths as the cold air passed through his lungs. Nothing, he felt nothing except for his rage. What spiritual gate was he supposed to meet? Why was nothing happening? He needed to focus, he had to concentrate on his spiritual gate and unlock it. He continued with his deep breaths, concealing his everlasting rage to complete this task. This cycle repeated for minutes on end as he channeled his breathing, he began to forget about the outside world as he focused inwards, into his core. It was odd, but he soon lost feeling and entered a meditative trance.

He opened his eyes and he stood in front of a tall, magnificent gate. There was nothing else but darkness surrounding him. So this was the spiritual gate. The only thing left was to open it. He propped himself in front of the door and pushed against it with all of his might but it didn't budge. He took a step back before shoulder-charging into the door, it still didn't budge. He looked around, attempting to see if he could locate any contraptions that could be used to open the door. Nothing, it was a simple gate. He tried pushing against it one more but but it was a futile effort.

The Slayer began to get upset, he was growing furious by this door and angrily punched the gate. He heard a slight crack as his fist made contact with the door, he looked at the area of impact to see the door had been damaged. He smirked and threw another punch with even greater force and dented the gate. If the gate wasn't going to open for him, then he was just going to break it down! The warrior began throwing a relentless series of punches at the wall, cracking it profusely as the damage spread to the entire gate. It wasn't long until the final punch shattered the entire gate.

The Slayer opened his eyes and he was back at the mountain, his breathing felt strange. His entire body felt light and he felt strangely focused, more so than before. What was this feeling? Did he do it? Is this what Urokodaki wanted the Slayer to perform? There was only one way to find out as the Slayer placed his helmet back on his head and decided to sprint down the mountain at full speed.

He was amazed by his speed but he was also surprised by his enhanced reaction time. Whatever this new power was, it was incredible. He was rapidly calculating his movements as he adjusted to the varying inclines and slopes he descended. He reached the trees and began weaving around them as efficiently as possible. It reached a point where he was simply moving too fast for his liking and dug his feet into the ground to stop himself. He skid across the ground for a few meters as his momentum carried him forward but his attempt to stop himself had succeeded. That's when he stopped concentrating, he had stopped moving so he was no longer focused on what he was doing and he felt the weight of his body return to him. It was a surreal feeling, it was like a switch flipped on his body. Urokodaki soon caught up to the warrior after a brief period and made a "hmm" sound before speaking, "You've seen what it's like to open your spiritual gate. Remember that sensation, that is what you must always strive for when tapping into your breathing techniques. Over time, you'll be able to constantly maintain that state and enhance yourself. Some of the best swordsmen are able to fight for ages without getting tired and it all boils down to proper breathing control."

The Slayer imagined what he was going to be capable of once he gets a good handle on this breathing business and the amount of ripping and tearing he'll be able to do once he's ready. This made him very excited to keep going and made him eager to keep learning.

They proceeded to the next part of the Slayer's training. To give the Slayer a break from exerting his lungs, he went back to swinging for an extended period of time. Using his arm blade, he easily burnt through several thousands reps before getting bored. He did find something interesting: he was able to burn through more reps in a quicker time. He wondered what that was about. On the other hand, Urokodaki was having the Slayer swing for even longer compared to yesterday which quickly became repetitive. Unfortunately, that is the nature of practicing.

He had to admit, this was very different from his training with the Night Sentinels. Yes, their weaponry was quite advanced and he learned to swing a blade there. However, the training there wasn't as intricate as this. The Night Sentinels were trained like soldiers, learning to swing their swords with purpose and taught to use all the tools in their possession. As he continued to swing, he began to realize how much him and the Night Sentinels had it easy with durable weapongry. They never had to worry about breaking their equipment as it was some of the most durable material in existence. Now the Slayer has to deal with fragile material that can break if a little too much force is applied to it.

Once Urokodaki felt the Slayer had enough swinging, he decided to shift gears to the final bit of training for the day. The warrior was taken to a nearby waterfall. Sakonji explains the purpose of the following assignment:

"The point of this is to work into the mindset of Water Breathing. As I said earlier, everyone's techniques are based on their spirit. However, a person can learn and strengthen their spirit to expand their arsenal of available breathing forms. I will test your compatibility with the Water Breathing technique by having you remain under the waterfall without your helmet."

Sakonji turned his back to the Slayer and took a seat on the grass. This gave the Slayer a bit of privacy to remove his helmet once more as he made his way to the waterfall. He positioned himself under the stream and took a seat. The water wasn't strong enough to push him down, but it got everywhere. The Slayer shielded his eyes by closing them, allowing the water to run down his face and onto the suit. Unfortunately, none of this was pleasant for the Slayer. It wasn't relaxing in the slightest because it was a waterfall.

Urokodaki chimes in and tells the Slayer, "Calm your mind, become one with the waterfall, let it soothe you." Nope, the Slayer was feeling none of that. The Slayer was more annoyed than anything else. He was tolerating the stream, but he was definitely not feeling at ease with it.

Urokodaki went against his word, keeping his focus on the Slayer to test how well he was adapting to the waterfall. He cared not what the Slayer looked like under the helmet, only if he's adaptable to Water Breathing. He could see the annoyance plastered on the man's face. The more he watched, the more concerned he grew for the Slayer as he couldn't see the man adapting like he should. There was absolutely no improvement in his state, it only worsened. He turns his head away right as the Slayer opens his eyes out of annoyance and puts his helmet back on.

The Slayer stomped towards Urokodaki who turned to him. The old man asks, "Are you done?" The warrior responded with an aggressive exhale which signaled to the older man that they were finished. They returned to the shed and settled down. By then, the sun was setting and it was time for them to hit the hay. It was a long day for them both and they went to their respective rooms.

Urokodaki sat on the floor and gazed upon a wall covered in other masks and swords. He takes off his red mask and sets it on the floor next to him. The old man has a gentle face with brown eyes, it opposed the fierce red mask he wore all the time. He eyeballed each item, taking in the craftsmanship of each of them. These were accessories his fallen students used to wear during their time under his teachings. At least, everything he was able to salvage. He couldn't collect all of their remains.

As he glanced over each item, he recalled the name of the student who died. It's always painful for the old man to remember their deaths. They died because of him and his faulty teachings. He sent them to fight demons and the majority died to the same one. That demon was one he captured and submitted to the Final Selection, which is an event that dictates who becomes a part of the Demon Slayer Corps or not. That demon, in particular, grew a hatred for Urokodaki and sought to end the lives of each student sent his way, all to spite the old man. After years of failure, he didn't want to send Tanjiro to meet his demise. However, the boy insisted on going and came back victorious.

After many years, he had success, but it doesn't excuse his failure. He still sent children to their deaths and he knew it. He grew lazy with each one and gambled their lives for success. Urokodaki couldn't forgive himself for such an atrocity. To pay respect to his fallen students, he asks them for forgiveness every night, bowing his head to the floor in shame as it was difficult for him to face the fallen remains of the students he cherished. The man's heart throbbed with pain every time, It never went away. With each student, he said their name and chanted, "I'm sorry, please forgive me." before moving onto the next. The man was at the verge of tears, going from student to student as the image of their deaths flashed through his mind.

"You can't lament over what you've lost; Only accept what you still have and move on."

The old man raised his eyebrows in shock and whipped his head towards the door to see the Slayer. The warrior said nothing else as he returned to his room. Urokodaki had to take a minute to process the Slayer's words and his voice. He begins to understand why the old master was so accepting of the Hellwalker. The warrior of legend has come in their time of need. Perhaps, he is the key to ending everything.

He looks to the belongings of his fallen students and realizes that if the Hellwalker is here to bring about peace, no more of his students have to suffer. However, the only way to make that reality happen is to have faith in the Slayer. It's up to him to train the Hellwalker to the best of his ability to assure that the future they yearn for becomes a reality. The demons will fear the Hellwalker, and nothing will get in his way.