Chapter 16: Pre-Selection Training

Due to excessive blood loss, Hatsune spent the entire day in a half-conscious state. Even when he woke up, his mind was foggy, unable to distinguish between reality and dreams.

At night, Seigen Ryoubei specially prepared chicken and fish soup to nourish his body.

Hatsune was surprised by how well an old man over fifty could take care of someone. He was at least better than the three chatty women at the Butterfly Mansion.

Despite the bitter taste in his mouth and his inability to taste much, Hatsune forced himself to drink two large bowls for a speedy recovery.

After dinner, Seigen Ryoubei set up a makeshift stove outside the wooden cabin, placed a large wooden tub from the storage behind the cabin on the stove, and filled it with water.

Hatsune, sitting on a stone stool by the door, watched Seigen Ryoubei bustling around. The warmth in his heart grew despite his gloomy mood.

His village was slaughtered, his sister abducted—he thought his life would be spent in despair. Yet, he first met the people at the Butterfly Mansion and now encountered this old man.

It felt as if some mysterious force was guiding him to these people.

Seigen Ryoubei was preparing a medicinal bath for him.

Already severely injured, Hatsune had been attacked by a demon the previous day. He not only lost a lot of blood but also had multiple wounds from the demon's claws.

Demon nails are poisonous, and the toxins were seeping into his body through the wounds. Seigen Ryoubei suggested a medicinal bath to expel the toxins while also improving his constitution, speeding up recovery, and reducing potential side effects.

Seigen Ryoubei ignited the firewood under the stove. Soon, steam rose from the wooden tub.

Testing the water temperature and finding it suitable, Seigen Ryoubei approached Hatsune.

"Should I carry you in, or will you walk yourself?"

Carry? He'd heard of carrying women but never men. Just thinking about it was cringe-worthy.

"No... no need, I'll go in myself."

Hatsune struggled to stand, supporting himself against the wall. He staggered towards the tub but soon felt his stomach churn and his vision blur. Eventually, he needed Seigen Ryoubei's help to sit in the tub.

Seigen Ryoubei sat on a low stool by the stove, occasionally adding firewood. The firelight highlighted his weathered face.

"Hey, old man, you talk so much. Why do you live alone on the mountain? Don't you feel lonely with no one to talk to?" Hatsune leaned on the edge of the tub, glancing at Seigen Ryoubei.

Seigen Ryoubei shot him a look. "Hmph, old man? No wonder the little butterfly said you're rude. Lonely? I don't stay on the mountain all the time. By the way, I reported your information today. You'll participate in the Fuji Attack Mountain selection in two months."

Hatsune turned to gaze at the starry sky and replied indifferently, "Whatever."

He was eager to join the Demon Slayer Corps to gather information about his sister on his own. Relying on others was unsettling.

With Seigen Ryoubei's meticulous care, Hatsune's body recovered significantly in just a week.

Though still unable to handle intense activities, he could perform simple movements without issues.

Seigen Ryoubei then devised a comprehensive rehabilitation and basic training plan for him, both to restore his health fully and prepare for formal training in a week.

Soon, Hatsune began his formal training, with a month and a half left before the Mount Fujikasane selection. He had to master the correct use of the breathing technique within this time.

The breathing technique, while merely an auxiliary method, was the essence of combat.

Unlike regular breathing, this technique involved inhaling a large amount of air in one go. Part of the air entered the bloodstream, speeding up circulation, raising body temperature, and temporarily unleashing the body's potential.

Another portion of the air filled the muscle gaps, indirectly increasing muscle density, providing cushioning, and enhancing resistance to blows. This was the ultimate effect of the breathing technique.

To truly master it, one needed strong cardiopulmonary function and physical strength. Otherwise, filling the muscles with air would place an unbearable burden on the body.

From the essence of the breathing technique, the stronger the body, the more effectively it could be utilized.

To effectively train Hatsune's cardiopulmonary function and physical strength, Seigen Ryoubei created a detailed physical training plan.

The six-week training was divided into three phases, each lasting two weeks.

The training included physical conditioning, agility and coordination exercises, sensory training, cardiopulmonary exercises, and combat skills training.

Every morning and evening, Hatsune had to run up and down the mountain. In the first phase, he ran without carrying anything. In the second phase, he carried five kilograms. In the third phase, he carried ten kilograms.

In the morning, he trained in a forest filled with traps and hidden weapons to enhance his agility, coordination, and sensory perception.

In the afternoon, he practiced sword strikes under a waterfall, divided into three phases.

In the first phase, he practiced normally.

In the second phase, he added two kilograms of weights to his wrists and ankles, totaling eight kilograms.

In the third phase, he added five kilograms to his wrists and ankles, totaling twenty kilograms. The wristbands could not be removed even during regular activities.

Besides practicing sword strikes, he also underwent cardiopulmonary training underwater, followed by Seigen Ryoubei's personal guidance in combat training.

Hatsune could only rest at night. However, this rest wasn't the usual comfortable sleep but rather meditation combined with the breathing technique to maintain his sensory perception.

This state, where even during sleep the breathing technique continued, was called "Total Concentration: Constant," a higher level of mastery.

Most in the Demon Slayer Corps were at the "Total Concentration" level, with only a few reaching "Total Concentration: Constant."

Achieving "Total Concentration: Constant" required exceptional aptitude and repeated training.

Though Hatsune could reach "Total Concentration: Constant," his experience was short, making his state unstable.

Often, he would maintain it well at night, only to revert to normal breathing by morning.

Even so, Hatsune's rapid progress amazed Seigen Ryoubei.

From their first meeting, he knew the boy was extraordinary—exceptionally intelligent and determined. The past few days of training confirmed his judgment.

No matter how rigorous the training, Hatsune completed it without complaint, unlike the struggles of others, even the mighty Himejima.