A week slid by, measured in ink lines and questions.
Ren found a rhythm quicker than he'd expected. Two hours a day with the Hokage's students, then another half hour after that for Tsunade to corner him with whatever she'd been chewing on since the previous lesson.
Tsunade took to fuinjutsu like she'd been starved for the right vocabulary. She'd show up early sometimes, forearms ink-smudged, muttering about flow bottlenecks in circular matrices. After class she'd linger, waiting until Jiraiya wandered off and the room quieted.
"I think the regulator array is overcompensating," she'd say, brows furrowed. "I can feel the chakra wanting to move here, but the seal forces it there instead, and the backlash—"
"Describe the pattern, not the feeling," Ren would remind her gently, and she would, and together they'd translate instinct into structure.
Orochimaru occasionally joined those extra sessions, his questions slicing cleanly at the edges of whatever problem Tsunade presented.
"If you're worried about cumulative strain," he observed once, "why not add a conditional release based on time, not just usage?"
Tsunade had stared at him, then at the page, then grudgingly admitted, "…That might work."
Jiraiya, to his credit, stayed. He doodled at first—little frogs in the margins of his notes—but somewhere around the second lesson, Ren noticed he'd stopped complaining about "pretty squiggles" and started asking why certain trap seals reset the way they did.
So when the ninth day came, it felt almost… normal.
He had them working on a simple layered seal—storage plus timed release—when the door slammed open hard enough to rattle the scroll racks.
"Urahara! We have a problem."
Captain Nara never raised his voice if he could help it. The fact that he didn't even bother to knock told Ren everything he needed to know.
He was on his feet before the chalk finished rolling off the table.
"Dismiss," he said simply.
Three heads snapped up.
Tsunade half-rose, frowning. Jiraiya froze mid-scribble. Orochimaru's eyes sharpened like knives catching light.
Ren didn't wait to see if they obeyed. He stepped around the low table and moved toward the door at a jog, falling into step with the Captain.
"What happened?" he asked, keeping his voice low.
Behind them, three pairs of sandals hit the floor.
Of course.
Ren rolled his eyes, but didn't turn around. The Captain shot a quick glance over his shoulder, saw the extra shadows trailing them, and grimaced.
"They might as well hear it," he muttered. Louder, he said, "Outer net pinged with an anomaly."
Ren's spine straightened.
"The Land of Fire net?" he asked.
"Yeah. Someone's pushing through," Captain Nara said. His mouth was a hard line. "The array shouldn't alert for just anyone at that distance as it's still having some difficulty telling the difference between civilians and shinobi. Sensitivity's not that high yet. However, whoever it's pinging has more chakra than some minor jinchuriki."
They turned down the corridor that led deeper into the HQ, toward the monitoring hall that had become Ren's second home over the past year.
"Classification?" Ren asked. "Tail count? Pattern?"
"No, it's not a jinchuriki," Nara said. "If they were, we'd be getting a very different sort of alarm. It's… raw and heavy, but not a tailed-beast signature." He flicked another glance at Ren. "The only reason we saw them at all is because that net of yours flexes when something it's too 'bright'."
Ren nodded once, mind already reaching for the internal schematic.
Before he'd joined the Corps, there had only been the Konoha barrier—rigid, ancient, beautifully stubborn. The idea of a wider net had existed as a footnote in old notes: "Land-wide sensory barrier—too complex, leave for later." Later had become him.
He'd built the Fire Country net to be different. Less monolithic, more modular. A living lattice instead of a stone wall. It had taken a year of proposal-writing, one year of researching it, and six months of actual construction, and it still wasn't perfect.
Refined enough to work. Loose enough to grow, but if someone was stressing it this early, that was… not ideal.
They stepped into the monitoring hall, and the world narrowed.
The giant translucent map of the Land of Fire floated in the center of the room, glowing lines marking the net's current configuration. The borders shimmered in pale blue, threads of chakra stretching like spiderwebs through forest, mountain, river.
Behind him, Ren heard three quiet intakes of breath.
He didn't look. Awe could wait.
"Report," Ren snapped.
One of the chūnin at the main console—it was always the younger ones here; older veterans still twitched at the strangeness of a three-dimensional projection—jumped slightly, then pointed with a trembling finger at a pulsing point near the eastern edge of the map.
"Here, sir. Eastern sea border. They breached the outer line two minutes ago. The net flagged an abnormal load. I traced it through the secondary grid—it's not dispersing. They're… too bright and moving too fast." His voice wobbled. "If they keep it up without us fixing it, they could tear that section because the Net cannot properly analyze it."
Ren stepped up beside him, eyes tracking the highlighted lines. The area around the marked point shimmered more violently, distortion rippling outward.
He frowned.
The net was holding, yes, but only because its flexibility allowed it to bend. Too much more and the threads would start to fray. And once a tear formed…
He didn't like the math on that.
"Show me the local matrix," he said quietly.
The assistant hurried to comply, switching the projection. A moment later, the broad map shrank to focus on a smaller area, magnifying the weave of seals there. Points of light signaled anchors. Lines pulsed with chakra flow.
Right there, in the midst of it, was a knot of stress that made his creation have problems classifying it, stressing it unnecessarily.
If they didn't adjust, the net would snap and destroy that section. If they overcorrected, it would snap because of them.
Either way, that section would go dark.
Ren inhaled slowly.
"All right," he murmured. "Let's see you properly, then."
Before his brain could talk him out of it, he clapped his hands.
Chakra snapped into alignment along familiar pathways, the way alchemical energy used to in another world. The net's structure unfolded in his mind's eye like a map being unrolled. He pressed one hand flat against the glowing seal array projected on the floor beneath the map. With the other, he covered his eyes.
The world flipped.
For a heartbeat, there was nothing but the sensation of movement—of his perception riding along the nearest anchor point, then leaping, following the tension along thread after glowing thread.
And then he was there.
Not physically. His body still stood in the hall in Konoha, one hand on the seal, one over his face.
But his sight hung high above a dark sea, looking down.
Waves rolled hard against jagged rocks. Mist clung to the surface of the water, curling around shapes moving fast along the shoreline.
Chakra blazed up from one of them like a bonfire.
Ren focused.
A boy—no, young man, older than Ren but not by much—moved at the head of a small formation of shinobi, cutting through the forest as if it were nothing.
Blue skin. Gills. Wild, spiked hair the color of midnight steel. Jagged teeth flashed when he barked orders. His forehead protector gleamed with the symbol of Kirigakure.
The chakra swirling inside him was dense, heavy, ocean-deep.
Kisame, Ren thought, gut going cold.
Not the monstrous swordsman he would become, but the seed of him. Already leading. Already dangerous.
"Male," Ren said aloud, voice calm even as his mind raced. "Tall. Blue skin. Shark-like features. Very high chakra reserves. I'd put him at… a low-level jinchūriki in terms of raw volume, but the pattern is human. No tailed-beast signature."
He felt three familiar presences close in behind him, listening.
"He's wearing a Kiri forehead protector," Ren continued. "Leading a small team of four. Their formation is tight. They're moving inland, likely following a planned route rather than wandering. They seem to be scouting."
His vision panned, tracking them for another few seconds, but there was only dense forest ahead. No obvious immediate target, no flash of a banner, no sign of a larger force.
He clicked his tongue softly.
"All right," he murmured. "That's enough sightseeing."
He let go.
The connection snapped back like a rubber band, and for a moment he swayed where he stood, the hall rushing in around him—ink, chalk, paper, the buzzing weight of too many eyes.
Ren dropped his hand from his face and, before anyone could speak, clapped again.
This time he pushed not outward, but inward, into the net's structure. His chakra slid along the same lines he'd just ridden, but with a different purpose: not to see, but to rewrite.
He found the node closest to the Kiri squad and adjusted its parameters, tightening the weave around the chakra profile he'd just observed.
High-volume, non-jinchūriki sources: flag as potential threat.
He layered in a minor reinforcement array, pulling extra strength from neighboring anchors, and attached a soft alert directive to the whole thing, routing updates directly to Konoha's main console whenever that profile shifted.
By the time he exhaled and dropped his hands, the local distortion on the map had smoothed out. The stress lines were still there—no seal could erase that much chakra—but they no longer threatened to rip.
Ren finally turned away from the projection.
The room stared back.
Captain Nara, a veteran who'd once watched a tailed beast from too close a distance, looked the less shaken. The younger chūnin sat frozen with brushes halfway to paper. Even Jiraiya's usual loud presence felt muted at his back.
Tsunade's eyes were wide, calculating. Orochimaru's were… hungry.
The Captain recovered first.
"What," he said flatly, "did you just do?"
Ren rubbed his thumb against his palm, grounding himself.
"Used the net as a lens," he said. "Followed the stress along the lattice until I hit the source. Short-range scrying, basically, just… stretched out a lot."
"And the second part?" Nara demanded. "You changed the pattern. I felt it. The anchors in that sector flared."
"I tightened the mesh around that chakra signature," Ren said. "Classified it as a threat category, the net now recognizes it and can categorize it, so it flexes with him instead of against him. It should hold."
"How far away was that?" one of the assistants whispered, looking at the map above them. "How can you see that far? There's no ink, no drawing, you just—"
"Clapped," Jiraiya finished weakly. "You just clapped."
Ren winced internally.
He'd really have to work on not doing that in front of an audience.
Out loud, he kept his tone even.
"The idea just… came to me," he said, which was true enough. "The net is already there. We designed it to transmit data. I realized, watching the distortion, that if I aligned my chakra with the flow, I could hitch a ride on the feedback and get a visual impression."
"Could we do that?" the assistant blurted. "Any seal-nin, I mean?"
Ren hesitated.
In theory? Yes. With enough control and understanding, anyone could use the net as a sensor extension. In practice… letting half-trained shinobi launch their senses across a continent sounded like a very fast way to induce chakra burnout and collective migraines.
"…Not like this," he said slowly. "Raw, it's too imprecise. And too easy to get lost in. I only managed it because I already carry a detailed map of the net in my head."
And because of Kisuke's intellect that has rubbed some off him, he did not say.
"But," he continued, "it should be possible to build an intermediary. An external focus—an object keyed to the net that channels the feedback in a controlled way. You'd anchor the array to something physical and let that do the heavy lifting."
Nara's eyes narrowed. "Like what?"
"A crystal," Ren said promptly. "Or a specially treated ink well. Anything that can hold a stable imprint of the net's pattern. Then you'd only need to sync your chakra with the object, not the entire lattice."
The Captain stared at him for another long moment, then dragged a hand down his face.
"Of course," he muttered. "Of course the solution is 'build another cursed invention.' Should've known."
He exhaled hard and squared his shoulders.
"All right. Draft me a proposal. Today, if possible. In the meantime, I'll send a report to Hokage-sama about Kiri's little scouting trip and your… methods."
Ren inclined his head.
Behind him, Jiraiya finally found his voice.
"Wait, wait, wait," he said, half outraged, half impressed. "You just looked halfway across the country, eyeballed some shark person from Kiri, rewrote a country-sized barrier on the fly, and your first thought is 'we should turn this into homework?'"
Captain Nara snorted.
"What else?" he said dryly. "We're not ANBU. We can't exactly go sprinting after every problem. We build systems that catch them instead."
Tsunade's gaze flicked from the map to Ren, expression sharp.
"You said his chakra is like a jinchūriki's," she said. "And he was already strong enough to stress the net."
"Yes," Ren said.
"Is that going to be… normal?" she asked. There was no fear in the question, only planning. "If we're going to see more like him, scouting inside the land of Fire, the Konoha-nin needs to prepare."
"I don't think he's normal, strength-wise," he said quietly. "But I think he might be a sign of what's coming, yes. Scouts from other parts will start to come."
Orochimaru's voice slipped in, soft as a blade.
"And this new classification you added," he said. "Will stabilize this…Net. Which we need now more than ever, now with a war coming close. Does the Hokage know about this invention?"
Ren met his gaze evenly.
"He accepted the proposal to work on it," he said. "We send the reports when we were researching it and when we finished it, and started implementing it. It's been six months since we finished it, but it's still a work in progress and we're constantly monitoring it."
Golden eyes flickered, interest sharpening.
"Has he come to see it?" Orochimaru asked. "He may know of it, but does he understand it?"
Ren resisted the urge to fidget. Instead he glanced to the Nara captain.
The man shook his head. "We informed him of our progress and of what we've done, but we also mentioned it needed refining it. Unlike the Konoha barrier, it's more flexible, so it's not a 'perfect' project."
"Which was something we needed it have," Ren said, deliberately matter-of-fact. "Perfection doesn't exit, it just means that you cannot update it further. Hard-coded barriers are strong but brittle. If we want this net to survive whatever the war throws at it, we need to be able to alter parameters quickly. Not counting that because the Land of Fire is bigger, we have more to take account of."
Nara cleared his throat, snapping the strange quiet that had fallen after that statement.
"Urahara," he said. "You're done teaching for today. Take a break of the hospital, too. You look like you've been hit by a genjutsu."
"I'm fine," Ren started automatically.
The Captain glared.
"That wasn't a suggestion," he said. "That kid in Kiri isn't going anywhere we can't see him now. We'll monitor his progress and let the Hokage decide what to do. Your job is to write up what you just did and not fall over from chakra exhaustion."
Ren opened his mouth to argue that he didn't have chakra exhaustion, and only then realized his fingers were faintly trembling.
…Fair.
He bowed instead.
"Yes, sir."
As the room began to disperse—assistants returning to their stations, messengers sprinting off with hastily written reports—Ren turned to leave.
He found his path blocked by three bodies.
Jiraiya planted his hands on his hips.
"Next time you pull something insane like that," he said, "warn a guy. I nearly peed myself."
Tsunade elbowed him in the ribs without looking away from Ren.
"That was… impressive," she said grudgingly. "Terrifying. But impressive."
Orochimaru said nothing at first. He just watched Ren, gaze intent, as if trying to peel back the skin and see the arrays underneath.
Ren shifted, suddenly aware of the echo of his future self's reputation breathing down his neck. Genius. Mad scientist. Man who tinkered with souls and bodies for curiosity.
"Don't get used to it," he said lightly, tugging the mask covering half of his face. "That kind of thing is expensive."
Jiraiya whistled low. "Chakra?"
"And focus," Ren said. "If I misaligned the connection, I could scramble my senses for days. Or cook parts of the net. Both would be inconvenient."
Tsunade's eyes narrowed thoughtfully. "Side effects?" she asked.
"Headaches. Nausea. Temporary disorientation." He shrugged. "I'll write them down for you later."
She nodded, satisfied.
Orochimaru finally spoke.
"You said earlier," he murmured, "that fuinjutsu is the code of the universe. That it can, eventually, touch anything built on chakra."
Ren inclined his head, wary.
"What you did just now," Orochimaru continued, voice low but thrumming with fascination, "looked a great deal like… rewriting the law of where you're allowed to see. And what counts as a threat."
Ren thought about denying it.
Then thought about the point of these lessons.
"Only within a very specific framework," he said. "And only because we built that framework first. I didn't change the rules of the world. I changed the rules of a net we wrote into it."
Orochimaru's lips curved, small and sharp. "For now."
Ren snorted softly.
"For now," he agreed. "Now, if you'll excuse me, I have a report to write before Captain Nara decides to throw it at my head."
He stepped around them and started for the door, feeling their gazes between his shoulder blades.
Behind him, he heard Jiraiya mutter, "And I thought this was gonna be boring."
Fuinjutsu, he thought, not for the first time, was both the safest place to hide and the most dangerous place to be noticed.
Too late to change that now.