"Looks like I can build a proper support puppet after all."
Kenji set Samehada down on the worktable in his tent. After several days of intensive study, he'd finally gotten a clear understanding of this bizarre weapon.
In his previous life, he'd seen theories that Samehada was somehow related to the Three-Tails, maybe a parasitic organism that fed on its chakra. Looking at the biological data he'd collected, that speculation wasn't completely off base.
Samehada was a weird existence. It occupied some middle ground between tailed beast and living creature, what he'd mentally classified as a semi-chakra organism. It had flesh and blood like a normal animal, with functioning organs and a circulatory system. But it didn't need food or water, produced no waste, and could survive indefinitely on pure chakra absorption.
The mouth full of serrated teeth? Purely cosmetic. Its feeding mechanism operated through direct contact, the scales on its body extracting chakra from anything they touched. The more chakra it absorbed, the larger it grew. He'd watched it expand by nearly twenty percent after gorging itself on his chakra reserves.
Most interesting was its preference for tailed beast chakra.
He had tested both the One-Tail chakra he'd sealed in his arm and the Eight-Tails chakra from the severed tentacle he'd acquired. Samehada had gone wild for the tailed beast chakra, its entire body vibrating. The sword clearly had refined taste when it came to its meals.
Unfortunately, Samehada appeared incapable of reproduction. As far as anyone knew, this was the only one in existence. Aside from its incredibly hard scales and chakra manipulation abilities, it didn't possess any overwhelming offensive capabilities. It was a utility weapon.
He'd even tried using the Mind Body Switch Technique to invade its consciousness, and to his surprise, it had worked. Samehada's mind was structured exactly like a nin-beast's, simple and instinct-driven but definitely sentient.
Despite its limitations, the sword had value. The ability to absorb chakra, transfer it to allies, and use stored chakra to accelerate cellular regeneration made it a natural support tool. He looked at the fearsome-looking blade on his table and couldn't help smiling. Something this vicious-looking turned out to be a dedicated healer.
He picked up a medical scalpel and carefully cut two scales from Samehada's body along with a small piece of tissue underneath. The sword immediately began trembling, its chakra signature pulsing.
"Fair trade," Kenji said, gathering red tailed beast chakra in his palm. He pressed his hand against the sword. "I'll compensate you."
As the Eight-Tails chakra flowed into Samehada, the wounds healed at a visible rate. New scales grew to replace the ones he'd removed, the tissue regenerating completely within maybe thirty seconds. The trembling stopped. The chakra signature smoothed out, even carrying hints of contentment now.
Samehada's blade surface rubbed gently against his fingers, the gesture reminding him of a cat seeking affection.
"Materials collected," he muttered, sealing the samples into a storage scroll. "I can build the support puppet later when I have time. Should be useful."
He was about to head to command when something caught his eye.
Through the tent flap, he could see one of the patrol teams returning from their sector sweep. The chunin leading them was holding a standard-issue map, trying to navigate by landmarks while his genin teammates argued about which direction they'd come from.
He frowned. Even with his sensory technique, coordinating patrol coverage across such a large area was inefficient. He could detect enemies within his range, but he couldn't be everywhere at once. And the patrol teams operated essentially blind until they encountered threats.
What he needed was better reconnaissance capability. Some way to survey the entire defensive sector from a safe position.
The idea had been percolating in the back of his mind for weeks, but watching the patrol team struggle with basic navigation crystallized it.
He needed sensor puppets.
Not combat units. Specialized reconnaissance constructs designed purely for information gathering. Different models for different purposes, night vision for operating in darkness, thermal detection for spotting enemies through concealment, long-range observation for early warning.
The simplest to implement would be a telescope puppet.
Mechanically, it was straightforward. He could mount adjustable lens arrays in the puppet's eyes, using a system of expanding tubes controlled by chakra threads. When he projected his consciousness into the puppet via Mind Clone Switch, he'd see through its eyes with magnified vision. Essentially turning the puppet into a mobile observation tower.
But the other sensor types would require more development.
Night vision... that one had him stumped. The principle was simple enough, amplify ambient light to make darkness visible. But implementing it with puppet components? He'd need to figure out some kind of light-amplification mechanism, maybe using special lenses or reflective materials that could gather and concentrate dim light.
Thermal detection was even trickier. Detecting heat signatures meant the puppet needed sensors that could register infrared radiation. He had no idea how to build those from scratch.
"I'll start with the telescope design," he decided. "Work out the basics, then tackle the harder stuff."
And beyond sensor puppets, there was another concept he'd been mulling over.
Flying units.
The tactical advantage of aerial reconnaissance was obvious. A puppet that could fly would provide a completely different perspective on the battlefield, able to spot enemy movements and troop concentrations from above.
He wanted to find a different method of flight instead of using Magnet Release like his Magnet Release puppet did. The chakra emissions would be detectable, potentially compromising the puppet's stealth capabilities. So he spent some time trying to work out alternative propulsion methods based on principles from his previous life.
Helicopters used rotating blades to generate lift. Fixed-wing aircraft relied on airflow over shaped surfaces. Drones achieved stability through multiple propellers working in coordination.
He'd tried sketching out designs for a rotor-based puppet, calculating blade angles and rotation speeds needed to achieve lift-off.
Then he'd realized he had no idea what he was doing.
The math alone was beyond him. Aerodynamics, thrust-to-weight ratios, gyroscopic stability... these weren't subjects he'd studied in either life. He was a ninja and a lab rat, not an aerospace engineer.
Most of his scientific background came from long, grinding hours in the forensic division at Miami Metro. He'd managed to slip into a vacancy left behind after one of their star analysts died during a coastal storm. The man had been famous for blood analysis. He, on the other hand, wasn't gifted in that at all.
His strengths lay elsewhere: cell work, micro-analysis, and the quiet, meticulous tasks that required a lot of patience. He'd become the guy they relied on for fine-detail biological examinations, the kind of work that never made headlines but solved just as many cases. Endless hours spent hunched over cultures, trace samples, and slides had built him a practical, almost automatic competence most people never noticed until they needed it.
And honestly, the job had been so demanding that it explained half the problems he'd had in his previous life. Miami Metro was supposed to be a normal forensic gig, but in that city, serial killers popped up like weeds. There was never enough staff, time, and definitely never enough money. He practically lived in the lab, surviving on instant ramen whenever he was home because it was cheap and fast, though whenever coworkers invited him out, he ate normal food to keep up appearances.
The workload also meant he almost never slept properly. By the time he got home after another double-shift, he was too wired to sleep yet too tired to do anything productive. So he'd crash in front of a monitor and lose hours to gaming or binging anime. Part escapism, part stress relief, part habit, and part necessity, since his side gig reviewing games kept him afloat financially. Late nights weren't just procrastination; they were the only time he had left for himself, and even that was squeezed between deadlines, debt, and the constant hum of lab equipment echoing in his ears.
He could still remember Masuka leaning over him with some wildly inappropriate joke, half mentoring him and half corrupting him. That guy was the one who threw random Japanese phrases at him, shoved questionable "learning material" at him, and then redeemed himself by recommending a few actually decent shows. Eventually, learning Japanese became practical: he couldn't rely on subtitles while working, and understanding anime on the fly made those late-night review sessions easier.
All of that had shaped his skillset, and weirdly fluent in Japanese thanks to a coworker who should never, ever be allowed near a language textbook.
But aerospace engineering? Designing propulsion systems?
Trying to reinvent flight from first principles was going to take years of trial and error.
"Fuck it," he'd finally said, crumpling up his latest sketch. "Magnet Release it is."
Ironically, using Magnet Release made the flying puppet problem trivial. He could create a lightweight frame, embed iron sand in the structure, and manipulate the entire thing through magnetic fields. Chakra detection be damned, functionality trumped stealth.
The real challenge would be mounting sensors on a flying platform without adding too much weight.
But that was a problem for later. Right now, he had a sword to deliver.
He grabbed Samehada and headed toward the command tent. He figured he'd hand the sword over to Shikaku and let Konoha's logistics department figure out what to do with it. He personally had no interest in using the thing. Fighting with Samehada always gave him the uncomfortable impression that he was beating people with a fish.
"How's the situation on the defensive line?" he asked, pushing through the tent flap.
"Don't ask." Shikaku rubbed his temples, looking exhausted. "The entire shinobi world is a mess. I heard Kiri started fighting both Iwa and Suna again recently. Right now, the Five Great Villages are basically all enemies. It's just one giant chaotic brawl. It gives me a headache. What a drag."
"War brings nothing but death and accumulated hatred," Kenji said. "But that's not our problem to solve. If you ever become Hokage someday, then you can think about how to fix things."
"I'm not becoming Hokage," Shikaku said after a moment of silence, his expression full of rejection. "Too much trouble."
Honestly, Kenji couldn't understand the logic of the shinobi world's conflicts. The major villages acted like rabid dogs, attacking anyone they encountered. In his previous life, even wars followed strategic principles, 'ally with distant powers, attack nearby threats,' diplomatic coalitions and counter-alliances. But the current shinobi villages? They fought any ninja from another village on sight, with zero strategy.
The most absurd example was the Lands of Wind and Water. Despite not sharing a border and being separated by the entire Land of Fire, they were fighting intensely. In the original timeline, Pakura had been handed over by the Fourth Kazekage to Kiri to be killed, all because of Third War grudges.
The other villages operated the same way. But after every war ended, aside from casualties, the villages gained almost nothing to compensate for their losses. What were they even fighting for? He truly couldn't figure it out.
"Anyway, I came to deliver something." He set Samehada on the table.
Since he hadn't bothered wrapping the blade in bandages, Shikaku got a clear look at it. He stared at it with wide eyes.
"You're telling me that's a sword?"
"Yeah, this thing right here." Kenji nodded seriously. "Don't underestimate it. Those scales are harder than steel, and it can absorb an enemy's chakra." He pointed at Shikaku with one finger. "For example, if it touched you, it could drain your chakra reserves in seconds."
"That terrifying?" Shikaku, who'd been leaning closer to examine it, immediately backed up several steps to maintain a safe distance.
"Only a jinchūriki can withstand its absorption rate. Oh, and it's alive, by the way," Kenji added. "You have to feed it chakra regularly to maintain it. Enemy chakra works best, but if you don't have access to that, you can use your own. If it likes your chakra's flavor, feeding it voluntarily can increase its affection level."
"What a troublesome thing..." Shikaku frowned.
"I'm done researching it, so I'm handing it over to you." Kenji turned to leave, completely uninvolved in whatever happened next. Then he stopped and added, "Oh, careful when you grab it. If it's unhappy, spikes will pop out from the handle and stab your palm."
"Then how were you holding it just now?" Shikaku asked quickly.
"Either your chakra suits its taste, or you force it into submission through violence. Those are your options."
Kenji started to leave again, but Shikaku stopped him. "Hold on, don't go yet. Let me have someone handle it first. Once we confirm everything's fine, you can leave."
He sighed but waited in the command tent. When the logistics ninjas arrived and attempted various storage methods, they all failed. Ordinary sealing techniques were completely useless. Samehada's chakra absorption disrupted every seal they tried to place on it. Unless they used a large-scale sealing array, the sword couldn't be stored safely.
Finally, Shikaku looked at Kenji helplessly. "Looks like I have to ask you to keep Samehada for now. I'll assign you a mission, 'escort Samehada back to the village.' You can take the opportunity to rest for a few days."
Kenji's eyes lit up. He'd been on the front lines for over half a year and needed a break. More importantly, he could check on his students and see how they were doing. "Sure, no problem."
He grabbed Samehada and strapped it across his back.