The Beginning of War

"I have a... bad feeling about this."

Just as Koshino was about to question Kakashi about his lateness, Kakashi's indifferent voice cut through the air, leaving Koshino stunned.

The sixth sense might be a vague concept, but after a breakthrough in his mental energy, Koshino's perception had significantly sharpened, making him more attuned to such feelings.

As soon as Kakashi finished speaking, Koshino felt a dark cloud hovering over him, causing his mood to become anxious and uneasy.

However, before Koshino could ask any questions, Kakashi's figure vanished with a swift "whoosh," leaving Koshino no time to inquire further. Suppressing the ominous premonition, Koshino stood there, thinking to himself, "Well, even if something bad is going to happen, it probably won't be immediate."

"If Kakashi said there's no mission for now, then I should focus on training."

"Yes! The shadow clones will continue the wind chakra nature transformation, while my main body will train in the Fourth Hokage's secret techniques and also spar with Guy."

"Guy usually trains in the same spot every day, right? I'll go find him."

Unsure of what exactly was wrong, Koshino decided that improving his strength was crucial.

After all, complaining wouldn't solve anything. The only thing Koshino needed to do was to keep strengthening himself. Even though he had reached the level of a chunin at just four years old, Koshino felt that his achievements were still not enough. With the feeling of impending danger, he set his sights on quickly attaining jonin-level strength.

For the next while, Koshino immersed himself in rigorous training every day.

He used the Multi Shadow Clone Jutsu multiple times a day to advance his wind chakra nature transformation training. 

Indeed, the shadow clone training method proved incredibly effective. 

Additionally, having mastered the Giant Rasengan and Finger Rasengan, Koshino's chakra control was already exceptional. Within a week, he had successfully "cut" leaves with his chakra, completing the first stage of wind nature transformation.

With this foundation, Koshino was ready to start learning some of the Fourth Hokage's secret techniques.

So, after the first week of training, Koshino sent his shadow clones to a small waterfall on the Nara clan's grounds to start the second stage of wind chakra nature transformation—cutting the waterfall.

In the original series, completing this training meant the wind chakra nature transformation was complete.

Once Koshino mastered this, powerful jutsu like the Wind Style: Rasenshuriken could be added to his repertoire using the app's accelerated learning. The Rasenshuriken, with its ability to be thrown, was exponentially more powerful than a standard Rasengan.

If he could master the Rasenshuriken before entering the battlefield, surviving would be much easier. Following closely behind the Fourth Hokage, Koshino felt confident he could make a name for himself in the ongoing war.

However, the second stage of wind chakra transformation was far more challenging than the first.

Three weeks had passed since Koshino completed the first stage. For three weeks, as a member of ANBU, Koshino hadn't received any word from the Fourth Hokage or Kakashi, spending his days in relentless training.

His chakra levels improved, his taijutsu training advanced with Guy's companionship, and the app's accelerated training buff made everything even better.

Carrying 20 kilograms of extra weight during training was a significant improvement.

The only setbacks were the incomplete new secret techniques in the app and the seemingly endless second stage of wind chakra transformation, causing Koshino some frustration.

Despite these challenges, Koshino's strength steadily grew.

Especially with the Fourth Hokage's secret techniques, Koshino's combat abilities were rapidly advancing!

After a month of intense training, Koshino was even pressuring Guy in their sparring sessions.

"Leaf Hurricane!"

"Boom!"

As their sparring began, Koshino and Guy removed their weights, and Koshino's body moved like the wind, launching a Leaf Hurricane towards Guy.

Caught off guard by Koshino's sudden speed, which seemed to surpass his own, struggled to keep up.

"Damn it, is this what being a genius means?"

"I've worked harder and trained longer than Koshino, so how is he this fast?"

Barely blocking Koshino's Leaf Hurricane, Guy prepared to counter, but Koshino's mid-air maneuvering and speed made his attacks relentless, pushing Guy to his limits. Feeling disheartened, Guy's morale dipped slightly. However, Guy quickly regained his composure and adjusted his mindset.

Koshino, on the other hand, was reveling in the sensation of "acceleration."

Using the Fourth Hokage's acceleration technique, Koshino felt the impact of the small but powerful secret technique on his overall speed.

Could Koshino truly match Guy's speed?

The answer was no!

But why was Koshino faster now?

The reason was the Fourth Hokage's acceleration technique and the augmentation provided by wind chakra!

In the original series, Sasuke managed to match Lee's speed within a month by utilizing lightning chakra to activate his cells.

Similarly, Koshino found the Fourth Hokage's wind chakra acceleration technique even more effective.

The more proficient he became with wind chakra, the faster his movements, helping him understand the origin of the Fourth Hokage's nickname.

Just as Koshino was starting to overpower Guy with his newly acquired speed, Kakashi suddenly appeared between them, causing both to frown.

After glancing at Koshino and then at Guy, Kakashi, with an expression of deep concern, took a deep breath and said:

"Guy, Koshino, stop fooling around. We need to gather at the Fourth Hokage's office."

"The war..."

"...is about to begin again!"