He lost count of the stairs leading down. The lantern was so dim it could not illuminate the grime in the cracks between the steps. The smell in the air changed. It was no longer the ink and rust of the floors above, but disinfectant mixed with medicinal herbs, with a faint, suppressed trace of blood that crept into his nose.
Orochimaru walked ahead, his black clothes brushing the wall almost soundlessly. The two Anbu behind them breathed tensely, their hands resting on their swords the entire time. Rinto glanced at them once and paid them no further attention, his eyes fixed on the signs on the iron doors to either side-sterile room, sample storage, live experimentation area. The paint on the lettering had chipped, but the words remained perfectly legible. The rough paper in his arms rubbed against his chest, and the hemp cord dug into him, but he had no attention to spare for that either.
The iron door at the bottom of the stairs was sealed. Orochimaru casually formed a hand seal, and it slid open. The lights inside were much brighter, a glaring white that made Rinto squint briefly. Then the entire laboratory seized his attention.
Shelves against the walls stretched from floor to ceiling, lined with rows of glass jars covered in densely written labels. He could not make out what was soaking inside them, nor did he care to look. A row of stainless steel benches stood in the middle, polished to a shine. On them lay engraving knives, chakra-measuring instruments, and metal components he could not name-all things he had previously only seen in ninja tool shop windows, never even allowed to touch. On the materials rack at the far end, everything had its own compartment: crystal jade, high-purity dark iron, and even several conductive crystals from the Land of Wind, gleaming beneath the lights.
A bespectacled boy was mixing medicine with his head lowered. At the sound, he turned and bowed slightly to Orochimaru. "Lord Orochimaru." His gaze swept over Rinto, and his eyes curved behind his lenses. He asked no questions, but looked him over from head to toe.
"Kabuto, leave us for now." Orochimaru waved a hand, his voice carrying its usual faint hiss, his manner careless.
"Yes." Kabuto set down his dropper, glanced at Rinto again, and slipped out, quietly closing the door behind him.
The moment the door shut, Rinto tossed the rough papers in his arms onto the nearest empty bench without even undoing the cord. His eyes remained locked on the materials rack. His first question was neither about the Cursed Seal nor their cooperation. "Can I take as much of that crystal jade as I want?"
Orochimaru froze for a moment, then chuckled, licking his lower lip as the interest in his golden eyes deepened. He leaned against the nearby lab bench, his fingertips unconsciously rubbing a rust stain along its edge. "Why the hurry? Tell me about that system of yours first. Let's see whether it's worth granting you that access."
Only then did Rinto look away. He pulled out a crumpled sheet of rough paper, grabbed the charcoal pencil on the bench, and began drawing. It was no neat schematic, just a jumble of circles and lines that would look like meaningless scribbles to an outsider. As he muttered, it sounded less like a lecture for Orochimaru than an offhand explanation of his own train of thought.
"When ninja refine chakra, they mash their physical energy and mental energy together into a mass that drifts around without direction. What are hand seals? They're a way of using your hands to draw a path for it, making it move in a fixed direction. Once it finishes, it disperses." He jabbed several crooked dots onto the paper. "What I do is engrave that path directly into iron or jade. Once chakra enters, it can only follow the patterns I've carved, and what comes out is the effect I want. No hand seals, no practicing nature transformation. Anyone who can refine chakra can use it."
Orochimaru's gaze settled on the paper, and his fingertips stilled. He had spent nearly twenty years researching ninjutsu. He understood the weight of those words better than anyone. People in the Shinobi World spent their entire lives practicing chakra control and hand seal speed. This boy had simply torn down the barrier to entry.
"Interesting." He leaned half a step closer, lowering his voice slightly. "Then tell me, where has my Cursed Seal experiment gotten stuck?"
Rinto raised his eyes, his charcoal pencil pausing on the paper. "I haven't seen a sample of your Cursed Seal. I only heard you mention it in the hall. It's essentially forcing a foreign chakra structure into a person's chakra pathways."
He casually drew two circles colliding, with a spike from one piercing the other. "It's like forcing a Fire Release pattern into a Water Release structure. The two repel each other. Either the pattern collapses or the medium explodes. If you want them to coexist, you don't need to make the Cursed Seal stronger. You need to smooth the edges of that foreign structure, make something to buffer it, so it can fit into the body's own chakra instead of being smashed into it."
Orochimaru's breathing stopped for half a second.
He had been stuck here for almost a year. Over a hundred test subjects had died, either bursting apart or going mad. He had always thought the subjects' constitutions were inadequate, or that the Cursed Seal's senjutsu chakra was not stable enough. He had never considered "structure." This boy had never even seen what a Cursed Seal looked like, yet with just a few remarks, he had struck straight at the root of the problem.
He stared at Rinto, the light in his golden eyes growing brighter, as though he had discovered a rare experimental specimen, yet with a hint of the excitement of finding a kindred spirit. "Can you make that buffering structure?"
"Yes." Rinto tossed down the charcoal pencil. "But I don't touch human experimentation. I can calculate models for you and modify the Cursed Seal's patterns, but finding test subjects and conducting live tests have nothing to do with me. I'm not responsible for cleaning up the mess afterward, either."
He had his own bottom line. In the laboratories of his previous life, the ethical boundaries had been welded firmly in place. He had no intention of crossing them in this life, either.
Orochimaru raised an eyebrow but did not press him. He had seen far too many people grovel at his feet for resources, and far too many madmen stop at nothing for power. This was his first time seeing someone who, with top-tier resources on offer, first drew a line for himself.
"Agreed," Orochimaru said readily. "As long as you can produce a workable model, you won't need to get your hands involved in anything else." He paused, then continued, "Rinto, work with me. You can use this laboratory as you please. Materials, equipment, samples—if Konoha has it, I can get it for you. Whatever you want, I'll provide."
"The conditions?" Rinto looked up at him without immediately agreeing. He knew there was no such thing as benefits for nothing. Someone like Orochimaru would never offer them without a reason.
"Two conditions." Orochimaru held up two fingers. "First, you must keep me updated on the core elements of your research. Second, whenever my experiments encounter problems involving chakra structures or pattern compatibility, you must help me solve them."
Rinto considered it. Neither condition was any trouble for him at all. His research needed experimental verification anyway, and showing it to Orochimaru meant another person could catch mistakes. Helping solve his problems would instead give Rinto access to samples he normally could not get his hands on, such as Cursed Seals and senjutsu chakra. He stood to gain with nothing to lose.
"I have a few rules of my own." Rinto laid them out clearly, one by one, without much emotion, as though he were stating experimental parameters.
"First, I want a private laboratory. Nobody can enter, including you. No one touches my data or unfinished work without my permission."
"Second, whatever materials or equipment I need, you have to get them for me. What I research is none of your concern. Don't ask."
"Third, I only help you with chakra structures. Everything else-human experimentation, forbidden jutsu development, killing, arson-has nothing to do with me. Don't come looking for me."
Orochimaru stared at him for several seconds, then suddenly laughed. His low, hissing laughter drifted through the spacious laboratory. "Agreed. I have no interest in you as a person. Only in what's inside your head, and those patterns you carve."
"Deal." Rinto nodded, turned, and walked straight toward the materials rack, paying Orochimaru behind him no further attention.
Orochimaru did not mind. He went to the door, opened it, and called Kabuto over. "Clear out the separate laboratory on the west side for Rinto. Give him full access to the materials storage. Whatever he requests, transfer it immediately. Get him an unrestricted access token as well. No one is to stop him anywhere in the Hokage building, including underground."
The smile on Kabuto's face stiffened for an instant, then quickly returned to normal. He bowed and answered, "Yes." In all his time serving Orochimaru, this was the first time he had seen his lord grant a stranger so much access, even opening the core materials storage to him without restriction. He could not help looking into the laboratory again. The boy in the coarse cloth tunic was standing on tiptoe to take crystal jade off a shelf, his eyes filled with nothing but that stone. He had not noticed anything happening at the door.
Kabuto withdrew to make arrangements. Orochimaru closed the door and turned to find Rinto bent over the lab bench, holding a palm-sized piece of crystal jade. He kept turning it over and feeling it, his fingertips brushing its surface, his eyes frighteningly bright.
Previously, all he had used were the cheapest dark iron scraps from ninja tool shops. They contained too many impurities and conducted poorly. Even engraving a simple Wind Release pattern required more than a dozen revisions, for fear the chakra inside would scatter or collapse. This crystal jade was different. It was exceptionally fine, and just pressing his fingertips against it, he could feel that chakra would pass smoothly through it.
"Can I take this to engrave something?" Rinto looked back to ask, already holding a diamond engraving knife—something he had never dared dream of before. A single one could buy more than half a year's food for him.
"Help yourself." Orochimaru waved a hand and went to a bench on the other side, pulling out his Cursed Seal experiment records. His mind was filled with the "buffering structure" Rinto had mentioned.
The laboratory fell quiet, save for the faint scraping of Rinto's engraving knife across the crystal jade and the rustle of Orochimaru turning pages.
Before long, Kabuto knocked on the door. He said the west-side laboratory was ready and asked whether Rinto wanted to look it over first so anything missing could be supplied. Rinto did not even raise his head. His knife hand never stopped. He merely waved his other hand and mumbled, "Leave it. Busy."
Kabuto said nothing more and quietly left.
Rinto lost all track of time. He poured himself entirely into that piece of crystal jade. Dense patterns he could not engrave into dark iron could be cut steadily into crystal jade, and the depth and spacing of every line were more than twice as precise as before. When he made a mistake at one bend, he clicked his tongue and spent ages smoothing it with a fine file. A layer of crystal jade powder coated his fingertips, but he paid it no mind.
The sky outside the window slowly darkened. The research and development department aboveground had long since emptied, but the underground laboratory's lights still shone dazzlingly bright. Orochimaru went out once. When he returned, he found Rinto still bent over the same bench, his posture barely changed, his back held straight and taut, his eyes less than a fist's width from the crystal jade. He was so focused he did not even notice someone entering.
Orochimaru did not disturb him and returned to his own compartment.
By the time Rinto finished the last line and set down his knife, his neck was so stiff that the slightest movement hurt, and his wrist ached so badly he could barely lift it. He shook out his hand, picked up the crystal jade, and held it to the light. The patterns were as fine and dense as strands of hair, fitting together perfectly without a single mistake or omission.
He walked to the jutsu-testing target in a corner of the laboratory, a thick steel plate specifically used to measure ninjutsu power. Holding the crystal jade, Rinto injected an extremely faint trace of chakra into it.
Pale blue-green light flashed. There was none of the previous rushing wind, only an exceptionally sharp hiss. When Rinto walked over to inspect it, the wind blade had already pierced the steel plate. The edges of the hole were as smooth as if they had been polished, without a single burr.
He picked up the nearby chakra meter and glanced at the readings, his eyes brightening. A dissipation rate of 6.2%, nearly half that of his seventeenth dark iron version. The range had tripled, and the power had more than doubled.
He grabbed a sheet of rough paper and rapidly jotted down the data with his charcoal pencil, still muttering, "Crystal jade really does conduct well. The loss at the bends is still a little high. I'll adjust the curves in the next version and see whether I can get the dissipation rate below 5%."
He never noticed that Orochimaru had come to stand behind him at some point. Orochimaru looked at the hole in the steel plate, then at the crystal jade in his hand, his golden eyes full of amazement. In three hours, he had doubled the power of Wind Release. This was not an improvement. It was a complete reconstruction of the logic of ninjutsu.
"If Konoha's Genin units were equipped with these things, their combat strength could double," Orochimaru said with a smile.
Rinto glanced back at him without much reaction, folded the paper bearing his data, and stuffed it into his pocket. "It's just basic optimization. Nothing worth talking about." To him, this was a routine experiment, not even a breakthrough. He had merely switched to a better medium and obtained the results he should have obtained.
He paused, remembered something, and added, "Right, I need chakra samples of different natures. Fire, water, lightning, earth. At least five of each, from people with different chakra reserves and different constitutions. You can get those, right?"
"Kabuto will deliver them tomorrow morning," Orochimaru said. "Never mind five. I can get you fifty."
"Thanks." Rinto nodded, turned, and took a smaller piece of crystal jade from the materials rack. He picked up his engraving knife, preparing to make another optimized version of the pattern, with absolutely no attention to spare for chatting with Orochimaru.
Orochimaru watched his back without disturbing him further. It suddenly struck him that finding a collaborator like this was much faster, and much more interesting, than blindly working himself into a dead end alone.
As dawn approached, the laboratory lights were still on. The rice balls Kabuto had delivered in the early hours sat in a corner of the bench, hard as stones, not a single bite taken. A blister had formed on Rinto's fingertip, and holding the engraving knife rubbed painfully against it. He merely frowned, wrapped it in cloth, and continued cutting.
His head was filled with patterns, transitional configurations for nature conversion, and compound structures he had never dared imagine before. As for Konoha's opinions, Orochimaru's schemes, or other people's awe, none of it entered his mind at all.
All he knew was that he could finally take a great step past the bottleneck that had held him up for almost half a year.