A week passed in a flash.
Kenji had settled into the rhythm of supply point life. Morning patrols along the three marked routes, occasional meetings with transport teams delivering supplies or evacuating wounded, and surprisingly long stretches of quiet in between. It was almost peaceful enough to forget they were stationed in a war zone.
Almost.
Every few days, a transport team would pass through carrying injured ninjas back from the front lines. Some were conscious and walking, others were carried on stretchers. The sight never failed to remind him exactly where they were and what was waiting out there.
But for now, his little corner of the war remained calm.
His students had improved significantly over the week. They'd memorized all three patrol routes, learned to move more quietly through the rain, and gotten better at spotting potential threats.
Today, though, he had something more important planned.
"Patrol's done," he said as they returned to the supply point entrance. "Don't run off to practice on your own yet. I'm going to teach you something new today."
The three of them perked up immediately. They'd been getting antsy, he could tell. A week of basic drills and patrols had left them eager for something more substantial.
"What are we learning, sensei?" Haruto asked.
"Chakra control."
"But we already know how to use chakra," Haruto said, looking confused. "They taught us that at the Academy."
Aoi and Kaede nodded in agreement.
Kenji shook his head. "You know how to access your chakra and push it through your body. That's not the same thing as controlling it efficiently. Right now, you're wasting massive amounts of chakra every time you use a technique. That means you won't be able to fight for long periods, which is a critical weakness."
That got their attention. All three were staring at him now.
"So... how do we fix it?" Aoi asked quietly.
"Through training that will make your body remember the proper chakra flow," Kenji said. He deliberately lowered his voice and made his tone more ominous. "Very difficult, exhausting training."
Aoi went pale. "How... how difficult?"
"Tree climbing."
There was a beat of silence.
"Tree climbing?" all three said in unison.
"Not regular tree climbing," Kenji clarified. "You can't use your hands, only your feet."
Before any of them could ask the obvious question, he walked over to the nearest tree. The rain had made the bark slick and dark, water running down the trunk in thin streams. He placed one foot against the surface, channeled chakra to his sole, and stepped up.
Then kept walking.
Straight up the vertical trunk like it was a normal path. When he reached a thick branch about fifteen feet up, he stepped onto the underside and hung there upside down, waving at his students below.
"Whoa!"
"That's insane!"
"How is that even possible?!"
All three of them rushed to the base of the tree, staring up at him with wide eyes and open mouths.
He dropped from the branch, landing lightly in front of them. "It's simple once you understand the principle. You concentrate chakra at the bottom of your feet. The adhesive properties of chakra make your feet stick to the surface. As long as you maintain the right amount, you can walk on any solid surface."
He pulled three kunai from his pouch and tossed them at their feet.
"The key is precision. Too much chakra and you'll blast yourself off the tree. Too little and you won't generate enough adhesion to stick. You also need to keep the flow stable."
Haruto picked up his kunai, staring at it like it might contain hidden instructions.
"Theory only gets you so far. Time for practical application. Each of you pick a tree and start practicing. Use the kunai to mark your highest point on the bark. Every attempt, try to go higher. You can take a running start at first to build momentum. Just find what works."
The three of them stood frozen, processing the instructions.
"Well? Get moving. The rain's not going to dry these trees anytime soon."
"Right!"
They scattered to claim their training trees. Kenji watched as they positioned themselves, studying the trunks like they were about to face down enemy ninjas.
Haruto went first. He backed up several paces, built up speed, and charged at the tree with his foot extended. The moment his sole made contact, he pushed chakra... and immediately flew backward, landing hard on his ass in the mud.
"Ow! What the hell?"
"Too much chakra," Kenji called out. "Scale it back."
Kaede tried next. He approached more cautiously, placed his foot against the bark, and pushed chakra more gently. He managed to stick for about half a second before his foot slipped and he face-planted into the mud.
"Not enough adhesion that time," Kenji said. "Find the middle ground."
Aoi took her turn. She ran at the tree, planted her foot, and managed to take two steps up the trunk before her chakra control faltered and she fell backward into a puddle.
"Better! That's the right general approach. Keep at it."
While watching their clumsy struggles, Kenji didn't let his guard down. His sensory ninjutsu was active the entire time, monitoring the surroundings. After all, this was still a battlefield, any moment of carelessness could lead to danger. Up until now, he'd only allowed his students to do taijutsu sparring and kunai throwing. Only after thoroughly mapping the terrain and confirming the area was temporarily safe did he allow them to start chakra-intensive training like tree climbing.
For the next hour, the clearing filled with the sounds of bodies hitting mud and frustrated cursing. All three students were covered in dirt and rainwater, their uniforms soaked through and plastered to their skin.
Kenji leaned against a nearby tree and pulled out his medical ninjutsu scroll. Might as well make productive use of the time.
The scroll had been his constant companion this past week. Every spare moment, he'd been studying its contents. He'd already mastered most of the techniques described, the Mystical Palm Technique and Delicate Illness Extraction Technique both came relatively easily once he understood the chakra flow patterns. Unfortunately, the scroll didn't contain any more advanced medical jutsu beyond those fundamentals.
Still, even basic medical ninjutsu was fascinating from a technical perspective.
The more he studied, the more obvious it became that medical ninjutsu and the medicine from his previous life were completely different systems. Sure, they shared some basic terminology like cells and organs, but everything else operated on entirely different principles.
Modern medicine worked through biological processes, chemical reactions, cellular mechanisms, and physical interventions. You understood the science and applied it systematically.
Medical ninjutsu just... did things. Basically miracles wrapped in chakra manipulation.
For example, wound healing in modern medicine required growth factors, careful treatment, and time for natural processes to work. The Mystical Palm Technique just flooded damaged tissue with yang chakra and directly stimulated cell division at accelerated rates. Infections that would require antibiotics could be extracted directly from the bloodstream using chakra. Even something as complex as cell cultivation, which would need sterile environments and carefully balanced culture mediums in his old world, could be accomplished here by mixing chakra into a nutrient solution and applying specific sealing techniques.
It was bullshit. Actual, literal magic disguised as a learnable skill.
And organ transplants? Those were even more absurd. In modern medicine, tissue rejection was a massive problem requiring careful matching and lifelong immunosuppressants. Here? Just shove the new organ in, use some medical ninjutsu to connect everything properly, and the body would accept it without issue. Sharingan transplants happened all the time in the series. People swapped eyes like they were changing contact lenses.
The entire medical system ran on "because chakra" as its fundamental operating principle, and somehow that worked.
He was still reading when a familiar voice broke his concentration.
"Sensei! I did it!"
Kenji looked up from his scroll. Aoi was standing on the trunk of her tree about ten feet off the ground, both feet planted firmly against the vertical surface. Her face was absolutely beaming with pride and excitement as she waved down at him.
He checked his mental timer. Not even three hours since they'd started.
"Already?"
That was impressive. Not quite on the level of Sakura from the series, who'd apparently nailed tree walking after just a few attempts, but still way above average. Even Sasuke had needed until the second day to get it consistently. Aoi's natural talent for chakra control was significantly better than he'd expected.
"Well done," he called up to her. "You've got real aptitude for this."
At his words, Haruto and Kaede both stopped what they were doing and stared at Aoi.
"No fair!" Haruto shouted. "How'd you get it so fast?"
"I just... did what sensei said?" Aoi replied uncertainly from her perch.
"She's a natural," Kenji said. "Some people have better chakra control than others. Aoi happens to be talented at it." He smiled slightly. "Since you succeeded first, you get a reward."
"A reward?" Aoi's eyes lit up even more.
"Wait, I want a reward too!" Haruto immediately protested.
"Me too!" Kaede added.
Kenji gave them both a flat look. "You want rewards? Stand on a tree like her. Until then, shut up and keep training."
"That's not fair!"
"Life's not fair. Get back to work."
Haruto and Kaede exchanged glances, then turned back to their respective trees.
Aoi walked down the trunk and jogged over to Kenji. "What kind of reward, sensei?"
Kenji reached into the sealed pouch on his vest and pulled out a scroll. He held it out to her. "Here, open it."
She took the scroll with both hands. When she unrolled it and saw the contents, her eyes went huge and one hand flew up to cover her mouth.
"This... this is a medical ninjutsu scroll! Is it really for me?"
"Of course it's for you. You've got exceptional talent for chakra control. That makes you perfect for medical ninjutsu. Study it carefully and practice when you can. Eventually, when someone on our team gets injured, we'll be counting on you to patch them up."
Aoi's face flushed red. She clutched the scroll tightly to her chest. "I won't let you down, sensei! I promise I'll study really hard!"
"I know you will."