"Suna's leadership knows they need us. Economy's still wrecked, military's not what it was. But the people?" He shook his head. "We beat them and they remember that. Every smile in that negotiating room had teeth behind it."
"Strategic necessity."
"Yeah." Minato picked at a seam on his vest. "I keep thinking about their genin. The ones who served tea during the meetings. They would've been, what, four during the worst of it? Five? And they looked at us like—" He stopped. "Anyway. It's going to break. Everyone in that room knew it."
"How long?"
"Years, I think. Maybe longer if the diplomats earn their pay." He stared at the ceiling. "Iwa's the bigger worry. Rebuilding faster than anyone expected. More territory, more people."
Tatsuya thought about patrol markers in wrong territory, the signs he'd noticed before the Kusa mission. "Kumo?"
"Quiet. Which is worse." Minato's expression was grim. "And Kiri's eating itself. Succession problems, factional stuff. Their Mizukage's losing his grip."
"So every neighbor is either hostile or unstable."
"Pretty much, yeah." Minato sat up fully, meeting Tatsuya's eyes. "The peace won't last. Five years, maybe ten."
They sat with that for a moment.
Then Minato's smile returned, smaller but genuine. "Your turn. Tell me about your exciting two weeks of not being stuck in a desert." The smile flickered. "Jiraiya-sensei said the Kusa mission got rough."
---
The eastern training ground was dark by the time Tatsuya arrived. Duy was already moving through forms, each strike precise, economical, devastating in its simplicity.
"You're late."
"Hospital meeting ran long. Then tea with Jiraiya. Then Minato needed to complain about sand for an hour."
"Friends are important." Duy finished his sequence and turned, settling into ready stance. "Two weeks is a long absence. Let's see what you remember."
No warm-up. No preamble. Just Duy's fist cutting toward his face.
Tatsuya blocked, pivoted, countered. The exchange was fast—faster than he could have managed six months ago. His body knew the forms now, muscle memory taking over where conscious thought would be too slow.
Duy pressed harder. A knee strike that Tatsuya barely deflected. An elbow that grazed his ribs. A sweep he had to jump to avoid.
"Your foundation is solid," Duy said between combinations. "Hip rotation improved. Power transfer clean." He caught Tatsuya's counter-punch and redirected it, using the momentum to spin him off-balance. "But you're still reacting. Still following."
Tatsuya reset his stance, breathing hard. "As opposed to?"
"Leading." Duy's smile was small, knowing. "You've learned to respond to attacks. Now you learn to create them."
"Create attacks? I attack plenty."
"You attack when openings appear. That's reaction." Duy circled slowly. "What if you could make openings appear? What if you could decide, before the exchange begins, exactly how your opponent will move?"
"That's... not how fighting works."
"Isn't it?" Duy's eyes glinted. "Attack me. Full speed, full commitment. Don't hold back."
Tatsuya hesitated, then launched forward. A combination he'd drilled hundreds of times—jab, cross, low kick, rising elbow.
Duy flowed around each strike like water. But more than that—Tatsuya felt himself being guided. Each block, each deflection pushed him slightly off his intended line. His weight shifted wrong. His balance compromised. And then—
His left leg came up in a high kick he hadn't planned. Momentum carrying him into a technique he hadn't chosen.
Duy caught his ankle and held him there, suspended and ridiculous.
"Left leg, high kick," Duy said calmly. "I decided that three moves ago."
"What?"
"What happens when you shift your weight left?" Duy released his ankle, letting him stumble back. "You close off the right side. Open the left. Your body picks the option that's available." He settled back into stance. "I just made sure only one option was."
Tatsuya stared at him. "That's... that's not just taijutsu. That's—"
"Five moves ahead. Sometimes ten. You position yourself so only one outcome is possible." Duy resettled into ready stance. "It takes years. But you're a medic — you already read systems for a living."
"Can you teach me?"
"I can show you the principle. Mastery?" Duy shrugged. "That's between you and however many thousands of hours you're willing to invest."
They sparred again. And again. Each time, Duy called his shot before the exchange—right cross, spinning back kick, desperate guard—and each time, Tatsuya found himself executing exactly that technique, pulled into it by invisible strings he couldn't see.
By the tenth round, he was starting to feel it. The faintest glimmer of how Duy was doing it. The subtle pressure on his lead shoulder that forced his weight back. The half-step that closed off his preferred angle. The rhythm of attacks that funneled him toward a single response.
"Better," Duy said, after Tatsuya managed to break the pattern and land an unexpected elbow. "You're beginning to see the cage. That's the first step to escaping it."
"So the second step is... doing that to someone else." He was still breathing hard. "Shit. That's terrifying."
"Now you're thinking." Duy rolled his shoulders, finally showing a hint of exertion. "Enough for tonight. Your body needs rest more than repetition right now."
Tatsuya grabbed his water, muscles aching in that good way that meant growth. "Same time next week?"
"If the village doesn't have other plans for us." Duy's cheerfulness had returned, but underneath it, something quieter. "You're improving faster than I expected, Tatsuya-kun. Don't let that make you careless."
"I won't."
He meant it.
---
Section Seven's developmental archives were exactly as Yamamoto had described: poorly organized, full of dead ends, and containing occasional threads worth following.
It was three in the morning. Tatsuya had given up on sleep after the second hour of staring at his ceiling, thoughts circling between Jiraiya's warning and the look on Minato's face when he'd talked about those Suna genin. The archives, at least, gave his brain a problem to chew on.
Kato's work had been filed under "Theoretical Frameworks—Incomplete," which was either a description of the research or an institutional judgment. The scrolls were old, the ink faded in places, the notation system unfamiliar. But the concepts underneath—
Tatsuya spread another scroll across the reading table, tracing the diagrams with careful fingers. What Kato had been working on was real. Not just healing, but information. Structured chakra that told damaged tissue how to repair itself instead of forcing regeneration through raw energy output.
Standard medical jutsu was brute force. Flood the area with chakra, overwhelm the body's natural processes, hope you don't run dry before the tissue stabilizes. Tatsuya had done it often enough to know exactly how fast your reserves cratered when the injury was bad.
Kato's approach was different. A template. A pattern of chakra that mapped healthy tissue structure and provided that information to damaged cells. Instead of the medic doing the work, the body would do it — guided by the template, using its own resources, healing from within rather than without.
The theory was elegant, it was the implementation, that was a nightmare.
Kato's notes were fragmentary, half-formed, interrupted by deployment orders and mission assignments and eventually, permanently, by whatever had killed him fifteen years ago. He'd been close to something, Tatsuya could see that. Close to a technique that could change battlefield medicine forever.
But he'd been thinking about it wrong.
Tatsuya pulled out his own notebook, began sketching modifications. Kato had tried to impose chakra patterns on cells, to force tissue to conform to external templates. That was still top-down thinking, still the healer controlling the process.
What if instead, you let the cells inform the pattern? Used the template as a communication channel rather than a command structure? The body already knew how to heal itself, it just needed time and resources. Give it a template that enhanced its natural processes rather than overriding them...
The mathematics were complex. The chakra control requirements would be astronomical. It would take months, maybe years, to develop anything functional.
But somewhere in these notes was a technique that could reduce the cost of battlefield healing by orders of magnitude. Tatsuya just had to find it.
---
Dawn found him still at the table, surrounded by scrolls and notes and sketches. His eyes burned. His hands were cramped from writing. His chakra reserves were depleted from experimental emissions, testing theories that mostly failed.
But he had a framework. A direction.
Kato's cellular templates, modified with Tatsuya's understanding of biological systems. Not a finished technique—not even close—but a path forward. A project that could occupy months or years of systematic development.
He gathered his notes carefully, organizing them into a structure that made sense to him even if it would confuse anyone else. The developmental archives would stay. These ideas were his.
The hospital was waking up as he left Section Seven. Medics arriving for morning shifts, patients being moved for procedures, the quiet bustle of a place that never truly slept. Tatsuya passed through it like a ghost, exhausted beyond the point of social interaction.
His apartment was dark and cold. He didn't bother with lights—just dropped onto his bed, letting the exhaustion finally pull him under.
The Gate was still closed. Jiraiya's warning was still rattling around in his head, and the war was still coming whether he slept or not.
But Kato's notes were waiting in Section Seven. That was a start.
Sleep came fast and dreamless.