The years began to feel like the thickening of concrete in Kagami's perception. The Founding Era (FE) progressed relentlessly, and the initial, provisional chaos of construction gave way to the hard, unyielding order of fixed routines, judicial precedents, and solidifying architecture. The Village was no longer a place dreaming of its founder's idealism; it was a functioning System, brutal in its efficiency and cold in its demands. Kagami, now a teenager, was enrolled in the new Academy, the first organ of this System designed to implant Tobirama's stringent logic into the minds of the next generation. His value lay in his flawless, robotic discipline, and his mind, which treated every problem—from basic Ninjutsu to clan logistics—as a purely logistical challenge demanding a surgical solution. At the Academy, he met those peers who formed the first generation purposefully melded together by the new, artificial structure: Hiruzen Sarutobi, Danzo Shimura, Koharu Utatane, and Homura Mitokado. They became the first Genin Team whose loyalty was to be forged not by archaic blood, but by the cold, impersonal logic of Konoha. Kagami saw his role not as a teammate, but as a silent, detached observer and technical analyst of this pivotal societal experiment, mapping the strengths and vulnerabilities of those who would one day inherit the seal.
Years passed, grounded deeply in administration and practical field operations. Early in their mentorship, Tobirama initiated the final, critical test of Kagami's commitment, pushing his student far beyond the theoretical lessons of Fūinjutsu and political control. During a low-level border skirmish, Tobirama ordered Kagami to sacrifice a small, strategically positioned Senju asset—a skilled messenger vital to a separate, minor flank—by deliberately delaying the handover of a critical scroll. The order ensured the man would be caught and executed by enemy patrols. The tactical advantage gained was minimal, but the moral cost was absolute, demanding the cold-blooded prioritization of System over Soul. Kagami executed the order without question. He filed the subsequent mission report with meticulous, inhuman care, ensuring the death was logged purely as an unfortunate casualty of war, neatly sealing away the messy truth. This singular, unfeeling act proved to Tobirama that Kagami's functionality was absolute and that his commitment to the System transcended not only Uchiha blood but also Senju affinity, solidifying his value as the ultimate, non-partisan controller. He had fully internalized Tobirama's chilling truth: the death that occurs to protect the Structure is valuable, while any death caused by weakness or emotion is merely chaos.
For Kagami, these foundational years were the practical testing ground for his ideology, forcing him to analyze and prepare the political ecosystem of the future. Hiruzen Sarutobi was the moral mirror, embodying a dangerous, yet essential, honesty. Kagami understood that the Village would eventually need a pure, unblemished symbol, and he began to subtly protect and steer Hiruzen's idealism. He intentionally sabotaged or adapted reports for missions that required moral compromise, always ensuring that Hiruzen's actions appeared strategically sound while remaining ethically pure, making him the perfect, uncompromised Symbol of Hope. Conversely, Danzo Shimura was the suspicious shadow who saw control as a means to personal power. Kagami recognized Danzo as the greatest internal risk to the system's stability—a man too volatile to rule, but too capable to discard. He subtly amplified Danzo's ingrained distrust through targeted, small leaks of misinformation and manipulated mission failures. This maneuver molded Danzo into the necessary shadow agent—the man who would protect Konoha from the outside, thereby laying the groundwork for a second, covert layer of control that Kagami could eventually manage and exploit.
Kagami's emerging dual role—the synthesis of ideals—was unexpectedly cemented when Hashirama Senju, sensing the rising political tension and Tobirama's increasingly cold planning, called the young Uchiha aside for a private conversation. Hashirama confessed he did not understand Kagami's cold methods or the absence of passion in his eyes, but he recognized the boy's absolute, unwavering devotion to the Village's survival. Hashirama asked Kagami to "protect the dream" in a way that his brother, Tobirama, with all his structural fear, simply could not, effectively entrusting the Uchiha with the spiritual mandate. This gave Kagami a final directive from both founders, cementing his belief that his unique purpose was to synthesize the two opposing forces: Hashirama's visionary dream, maintained through Tobirama's calculated, unforgiving structure.
He used these years to perfect his Genjutsu abilities, not for battle or torture, but for the adaptation and stabilization of reality. He was the unseen editor, removing the inconvenient strings from the memories of others to keep the illusion of peace perfect and the populace docile. This ability became his tool of political architecture, and he immediately used it to prepare the Hokage successor. Kagami subtly engineered a high-stakes scenario that forced the Genin team to choose between Danzo's ruthlessly practical solution and Hiruzen's idealistic, compassionate one. Kagami then used his refined Genjutsu skills to manipulate the perception of the resulting damage and subtly enhance the outcome of Hiruzen's choice, making the compassionate path appear demonstrably superior for the Village's stability and public image. This was the perfect demonstration for the elders of Hiruzen's ideal Hokage material—a demonstration orchestrated entirely by Kagami.
With the commencement of the First Shinobi War (16 FE), when Kagami was twenty-two, his childhood definitively ended. He joined the ANBU and quickly became Tobirama's constant shadow and chief covert operator, viewing the war not as conflict, but as a systemic purge of the chaotic elements outside Konoha's walls. For ten long years, Kagami served, his Sharingan witnessing thousands of deaths, his body aging, and his mind hardening further as he consistently prioritized the logic of control over morality. The War neared its end (26 FE), with Kagami now 32 years old. The final major battle lay ahead—the battle against the Kinkaku Force—the battle that would end the War but claim the life of his mentor, Tobirama Senju. Kagami attended the final mission briefing and based on his own strategic analysis and Tobirama's ruthless self-assessment, he knew this was the mentor's calculated exit, the final sacrifice for the System's health. Tobirama's survival would create a power bottleneck, freezing the generational change and risking stagnation; his death allows the system to flow cleanly to the next generation (Hiruzen), stabilizing the political environment. Kagami viewed his mentor's impending death not as a tragedy, but as the ultimate, calculated price of Tobirama's own ruthless logic, necessary for the consolidation of the System.
He saw the finalized map of Konoha not just as a chessboard, but as a massive, complex sealing matrix. He was no longer an Uchiha, nor a student, nor a player; he was the future Control Mark—the emotionless guardian at the very heart of the greatest seal ever designed. His mandate was absolute: The Illusion must become Reality.