Naruto: Aizen's Shadow in Konoha

After by his victory against Minato, Aizen set his sights beyond Senju Nawaki. His ambitions soared – the entire ninja world, even the future Fourth Ninja War! It was a lawless era rife with powerful individuals. Even Kage-level fighters, the pinnacle of power at that time, were like ants compared to what was to come.

However, Aizen wasn't naive. The immensity of his goals wasn't lost on him. His initial euphoria was tempered by a swift return to reality. He concealed chakra, a level undetectable by even Genin.

Fortunately, his diligence paid off. Two days ago, he finally achieved the chakra reserves of a Genin! This marked a significant power upgrade. In a rematch with Minato, Aizen was confident of emerging victorious.

However, within the vast landscape of the ninja world, Aizen was still a fledgling Genin, far from the true powerhouses.

Despite his intense training, Aizen maintained his daily school attendance. Unlike other transmigrators who began with immense chakra or kekkei genkai (bloodline traits) like the Rinnegan, Aizen had only the memories of Sosuke Aizen's Shinigami life and his Zanpakuto, Kyoka Suigetsu. Everything else he had to achieve through sheer effort.

To his growing frustration, the system he expected offered no assistance, rendering it practically useless.

Today marked the official start of the combat class, though it wouldn't begin until afternoon. Aizen, however, sought a different kind of training in the morning. He ventured to a special location within the academy – the medical room.

He wasn't there for treatment, but to learn medical ninjutsu. Unlike the later, more formalized Konohagakure, the medical ninja system was still in its nascent stages. The academy offered basic medical knowledge and techniques to students interested in this specialized field.

The First Ninja War had just ended, and Konohagakure was in a rebuilding phase. The concept of medical ninjas integrated into combat squads hadn't even been formally proposed. Tsunade, one of the Sannin, would later advocate for such a system after the death of Nawaki, but it wouldn't be adopted until the Third Ninja War. With the Second Ninja War still on the horizon, Aizen saw an opportunity in this undeveloped field.

Unlike their modern counterparts, Konohagakure's medical ninjas weren't always deployed directly on the battlefield. Aizen, with his talent for chakra manipulation, saw an opportunity. By entering the medical field after graduation, he could potentially avoid the Second Ninja War entirely. Even if forced to participate, he could aim for a safer role in the rear guard, tending to the wounded.

This, it seemed, was Aizen's primary motivation for learning medical ninjutsu – to ensure his survival during the war. Some might consider this cowardly, a stark contrast to the typical protagonist in a Naruto fan fiction. These heroes often thrived under the pressure of war, their strength growing exponentially in such dire circumstances.

Aizen, however, held a different view. In his eyes, the supposed "immortality" some protagonists possessed was nothing but plot armor. Many would likely be dead without it. While he acknowledged that ninjas honed by war were undeniably formidable, he believed true strength came from steady, incremental progress, not just battlefield baptism.

Of course, for those with Saiyan blood , the situation might be different. But for Aizen, self-preservation during this tumultuous time wasn't shameful; it was a necessity.

Here's the crux of the issue: unlike many fan fiction protagonists, Aizen wasn't born into a safe era. Most fan fiction places the protagonist in a generation after Minato, often between the Second and Third Ninja Wars. This allows them to develop their skills before the real conflict begins.

Aizen, however, had no such luxury. He was thrust into a world on the brink of another war. With only a year to reach Chunin rank, the battlefield was a guaranteed death sentence for him.

So, while mastering medical ninjutsu might seem like a cowardly tactic, it was also a strategic move for his future. With his talent, Aizen was confident he could reach Kage-level or even surpass it, assuming he survived.

But beyond Kage-level lay the Six Paths level, a realm reserved for the descendants of the Sage of Six Paths. It was considered the pinnacle of achievement attainable through bloodline. The only exception to this rule was Might Guy, who, through sheer willpower and the Eight Gates technique, nearly defeated the Six Paths Madara.

However, Might Guy's feat was a temporary anomaly, not a true reflection of Six Paths-level power. This led Aizen to question the absolute nature of bloodline limitations. As a former biologist, he refused to believe that certain aspects of life were unbreakable. He believed the key was yet to be discovered, and that science held the answer.