Black Zetsu's plan, in theory, was perfectly smooth. The only problem was that reality refused to cooperate. Having Madara and Shirou meet in Konoha was, to put it mildly, unrealistic.
Mito's sensory abilities were so potent that Madara couldn't so much as sneeze in the Land of Fire without setting off alarms.
Case in point: when little Tsunade returned to the village alone, Mito immediately sensed Madara's presence, throwing the entire village into a panic. Without Hashirama, no one but Mito herself felt they stood a chance against him.
It wasn't until Shirou returned, casually explained that Madara had just come to pay his respects, and vouched for the situation with his own unassailable credibility that everyone managed to unclench.
"Hmph," Tobirama fumed upon hearing the news. "That bastard kills my brother, and he still has the gall to show his face in Konoha to 'pay respects'?"
As much as it grated on him, he was helpless. No one in Konoha could hunt Madara down now. And besides, there were more pressing matters. Reports from the border smelled of gunpowder. The Sand Village was getting bold. War was coming.
As Konoha slowly emerged from its grief, the village watched as the Second Hokage, Tobirama, began a series of sweeping reforms. He established a medical ninja training department, overhauled the Academy, and expanded the ANBU.
Then, there was the Uchiha problem. With Madara still at large, the Uchiha clan was a ticking time bomb in Tobirama's mind. He couldn't just eliminate them, so he opted for a more... elegant solution.
He promoted a promising young Uchiha named Kagami to his personal guard. Then, he put his long-prepared surveillance plan into action. The Uchiha were "gifted" the responsibility of forming the Konoha Military Police Force, a separate entity responsible for policing the village and guarding the prison on its outskirts.
The exclusion was painfully obvious. Some within the clan grumbled about the blatant segregation. Others, with a more "glass-half-full" perspective, saw it as proof that they were still the most powerful clan in Konoha, especially now that the Senju had all but disbanded. Any who tried to oppose the policy were swiftly arrested. The Konoha Military Police Force was a done deal.
"Everything is for Konoha," Tobirama dismissed any complaints with a single, unyielding sentence. "At a time like this, there can be no internal chaos. War is already inevitable."
And the war came quickly. Faster than even he had anticipated. The Sand Village launched a full-scale invasion, crossing the Land of Rivers and striking deep into the Land of Fire.
At first, people thought it was just the Sand trying to grab some fertile land. But soon, the entire ninja world was engulfed in flames. The Stone, the Cloud, even the Mist from across the sea—everyone jumped into the fray, hoping to pick at the scraps of victory.
Tobirama's strategy was simple: attack the weak, defend against the strong. Konoha would first crush the Sand Village, then turn its attention north to fend off the Stone and Cloud. The south was left to the Uzumaki clan in the Land of Whirlpools, Konoha's steadfast allies.
The plan was sound. If they could just hold out, the Cloud and Stone villages, natural rivals, would inevitably turn on each other.
Tobirama was, all things considered, rather optimistic. He didn't even interrupt the normal operations of Konoha. The Academy children still attended classes, though their teachers were now chunin, and the curriculum had been stripped down to the basics.
"The old teacher went to the battlefield," the kids would whisper. "I heard a lot of people from the village died. That jumpy kid from the class next door? Both his parents are gone."
Little Tsunade had also started at the academy. She went to school during the day and snuck off to the hospital at night to continue her training with Shirou. The front lines were desperate for medical ninja, leaving the hospital short-staffed and overwhelmed with wounded soldiers sent back from the battlefield.
This was, in fact, another of Tobirama's brilliant, if morally dubious, orders. After a single inspection of a battlefield aid station, he'd had a thought. On the principle of "bullying the good guy," he ordered his medics to conserve chakra on the seriously wounded.
They were to perform only the most basic first aid and ship the soldiers straight back to Konoha, where the "idle" Emiya Shirou could handle them. It was a brilliant measure, and it saved countless lives. Tobirama knew Shirou, a man certified as a "good person" by the Sage of Six Paths himself, would never refuse to help.
And indeed, Shirou was saving people. A green chakra floated in his palm as he gripped a patient's heart, manually keeping it beating while his other hand, guided by chakra threads, sutured the delicate wounds.
"Tsunade," he said, noticing her arrival. "Go to the next room and wait. This surgery will be finished soon."
"I'm not afraid, Lord Emiya," she said, stepping closer, a green chakra already glowing on her own small hands. "I can help, too!"
"Then listen," he said, beginning his lesson even as he worked. "These chakra threads promote healing. For internal surgery like this, you control the Yang-nature chakra to form the threads. This way, the patient won't need stitches removed later. The threads will disappear on their own."
"Mmm," she murmured, carefully handing him a piece of gauze.
"Thank you," he said, dabbing at the wound. "The number of wounded seems to be increasing lately."
"You're the one who's working harder," she replied, a hint of sadness in her voice. "Lord Emiya, how can we save more people? There's only one of you."
"Higher medical skills," he said. "More surgical experience. A more determined mentality."
He waved for an assistant to wheel the patient away, then washed his hands with a ball of water conjured in his palm. His voice dropped to a near-whisper, so low that even she could barely hear it.
"And most importantly, greater power."