Crossover Anime: Starting with Bankai from Demon Slayer

That wasn't the crude fistfight of street thugs, nor was it his clumsy knife skills when he casually swung his sword with brute force and ferocity.

This strike is more like a resonance between the human body and nature, the ultimate power unleashed by the human body, a wild display of force between heaven and earth!

The wooden sword was swung upwards, unleashing a storm!

"The teacher was very serious today..." Rika suddenly said.

With Arashizaki Teshin as the origin, a tornado composed of pure, violent air currents suddenly formed and rose from the ground!

Rumble!!

A violent wind pressure poured out from Arashizaki's wooden sword, instantly sweeping across most of the training ground!

The murky snow and sand mixed with the dust from the training ground, instantly forming a sandstorm several meters in diameter that shot straight into the sky! It was like a roaring, yellowish-brown python, frantically stretching its fangs towards the heavens!

The edge of the tornado emitted a piercing cutting sound, and sharp wind blades visible to the naked eye darted up and down within it. Asuka had no doubt that if she touched it, she would be instantly sliced ​​through flesh and blood!

A moment later, the howling tornado gradually subsided, and the snow and dust that had been swept up in the sky fell like raindrops, forming a clear circular area around Arashizaki Teshin.

He slowly withdrew his stance, the wooden sword pointing diagonally at the ground, his breathing gradually becoming steady.

Arashizaki Tesshin cast his deep gaze upon the stunned Asuka, and spoke in a low, powerful voice, "Do you see that? To kill those demons, brute force and the ruthlessness learned from the streets are not enough!"

"If you're willing, I can teach you the Breath of the Wind, which will give you the power to fight demons, but you must also shoulder the responsibility..."

"Asuka, are you prepared to become a Demon Slayer?"

The resolve to become a Demon Slayer? Asuka paused for half a second, then quickly dismissed the thought.

He didn't feel much about killing ghosts or anything like that.

In Asuka's view, although he didn't know where ghosts came from, the fact that ghosts ate people, just like dogs fighting over food and wolves eating sheep, might be one of the rules of this cruel world.

He had already avenged the old man with his life; the other ghosts had nothing to do with him.

Whether it's the Demon Slayer Corps or the God Slayer Corps, he doesn't care what these people want to do.

But power... this old man possesses a very strong, learnable power!

He wanted to survive... to live better and safer, and that required him to acquire greater power!

"...Okay, but how many of those monsters do I have to kill to get this cultivation method for power?"

Arashizaki Tesshin gave him a deep look.

The wildness in the boy's eyes hadn't faded; he was like a lone wolf just rescued and returned to its pack... The will to survive at all costs is the cornerstone of becoming a powerful swordsman, but it's also a risk...

In this increasingly turbulent era, the Demon Slayer Corps also needs more new recruits...

He hesitated for a moment, but then made his decision: "You don't need to switch... Since you've made up your mind, you can stay and train with us starting tomorrow!"

Thus, Seventy-Eight Birds, this otherworldly stray dog ​​from the lowest rung of Rukongai, remained at the Hayama Breeding Center.

In the beginning, Arashizaki Tesshin did not teach him anything about sword techniques or combat.

Every day begins with the fiercest morning wind at the mountaintop.

Arashiki Teshin gathered his disciples and had them sit cross-legged in the cold outdoor training ground, close their eyes and concentrate, feeling the cold and fierce mountain wind.

"Wind Breathing is the most agile and swift style, as unpredictable and powerful as a whirlwind!"

"Feel the air entering your mouth and nose, flowing through every inch of your trachea into your lungs, and then slowly exhaling!"

"Don't rush your breathing! Imagine yourself as a bellows, pushing yourself to the limit with each inhale! With each exhale, completely empty your lungs, like a hurricane sweeping across the earth!"

Asuka listened to Arashi's request and wondered what was so difficult about it.

He tried several times as instructed, but Arashi's wooden sword mercilessly struck his diaphragm with precise and ruthless force, causing him so much pain that he could barely breathe.

"Too shallow!" Arashizaki snapped. "Rhythm! Maintain a steady and powerful rhythm!"

Asuka got up, gritted her teeth, and tried her best to do exactly what Arashi had asked.

He soon learned his lesson.

In the fierce mountain wind, the air felt like knives, making people feel suffocated. Asuka and the others had to follow Arashizaki's instructions and breathe at a frequency and depth far exceeding that of ordinary people, trying their best to feel every bit of airflow.

Countless invisible needles were repeatedly stabbing his trachea and alveoli, and he felt a tearing sensation in his lungs. Every breath felt like a blade going in and out of his trachea!

He could only hold on for less than ten minutes before his vision went black, his ears started ringing, and he began to cough violently.

"Hmph! You can't even endure this little bit of hardship, yet you want to master the power of the wind?" Kenichi was also sitting cross-legged and breathing exercises, but his progress was much deeper than Asuka's, so he naturally wasn't in such a sorry state.

He openly sneered at Asuka, and Arashi tacitly allowed this to happen, silently observing Kenichi intentionally provoking this wild boy he disliked.

But Asuka ignored Kenichi's mockery, simply wiping the saliva from the corner of her mouth with her sleeve, calming herself down once more, and trying again.

Compared to the days of living in constant fear and uncertainty, like a lost dog, what is this little pain?

Arashi quietly observed the almost obsessive persistence in Asuka, sensing his clumsy and rough nature, yet also his wild and relentless struggle, his expression serious.

This kid has a ruthless streak... He'll use every last ounce of strength he has to achieve his goal...

One day, two days, three days...

Asuka became the first to arrive and the last to leave the training ground.

The morning frost had not yet melted away when he was already sitting cross-legged on the cold stone slab. Even after everyone had left, he had not yet come out of his meditation.

A tearing pain shot through his lungs, and his clothes, soaked with sweat, quickly grew cold in the wind, sticking to his body with an icy chill, but he chose to endure it.

Sometimes, when he practiced until he was exhausted, he would faint on the cold stone slab, and be found by Pear Blossom on patrol and dragged back to his room.

But the next day, he still showed up on time, his eyes even more determined.

Kenichi's mockery gradually turned into silence, and then into an incomprehensible gaze.

He watched with his own eyes as the birds fell down time and time again, only to rise again and again.

That wasn't training; it was a desperate struggle, like burning their lives for a chance to become stronger.

This ruthlessness made him feel pressured, and even... admired.

When Asuka was finally able to maintain this breathing for more than half an hour despite the intense pain and no longer fainted, Arashizaki handed him his first training wooden sword.

"Physical training will begin tomorrow!"

This does not mean liberation, but rather a more painful ordeal.

In the indoor training area, Arashizaki demonstrated the most basic sword-holding posture: "Without a solid foundation, even the most elaborate techniques are just castles in the air. Keep this firmly in mind!"

Thus began Asuka's maddeningly monotonous basic sword-wielding training.

Chop! Slash! Slash! Thrust!

Time and time again, day after day, the birds repeat the simplest and most monotonous movements.

Holding the heavy wooden sword with both hands, he carefully swung it according to Arashi's instructions regarding every angle and every force.

Every swing of the sword must be coordinated with the rhythm of breathing.

Inhale, gather strength

Swing the sword, unleash a burst of power.

Exhale, finish the movement.

The movements must be precise, and the breathing must be synchronized.

Kenichi and several other classmates, after completing the required number of sword swings, went on to practice more complex footwork or sparring.

Only the birds, like tireless machines, remained standing in the same spot, swinging their wooden swords again and again.

My arms felt like they were made of lead, and each lift was incredibly difficult. The rough wooden handle chafed my thumbs and forefingers, and blood seeped out and dripped into the hilt of the sword. Sweat flowed into the wounds, bringing excruciating pain. My lower back ached unbearably, as if it would break at any moment.

"That's enough! We've finished today's training! Do you want to ruin yourself?" Kenichi finally couldn't hold back and shouted at Asuka, who was still doing extra training, after a training session.

Feiniao's movements did not falter at all, sweat dripped down his taut jawline and onto the wooden planks beneath his feet, without uttering a word.

He didn't know what muscle soreness was; he only knew that his back would hurt even more when the thugs' sticks came down!

Morning, dusk, noon, evening, and even late at night.

Thousands of times, tens of thousands of times, hundreds of thousands of times...

The blisters on my hands broke and scabbed over, eventually turning into a thick layer of calluses.

This went on for seven months.

Until Kenichi told him with admiration:

"...Asuka, you're amazing! The teacher said you can start your [off-site training] tomorrow!"