Finn had turned to say something to Kakuzu and Sasori when he felt it.
Inside the compressed sphere of earth and stone, the Dark-Dark Fruit was doing something it had not done before. He could feel it working against the Susanoo's chakra structure the way it worked against the abilities of Logia users back home: consuming, drawing inward, converting. The Susanoo was dense chakra given form, and the darkness was eating it with the focused appetite of something that had found food it recognized.
He turned back to the sphere and stood very still for a moment, thinking.
He had assumed, when he first arrived in this world, that this particular property of the Dark-Dark Fruit was effectively dormant. Back home, it meant something specific: the ability to absorb and negate the powers of other Devil Fruit users, to strip away what made them exceptional and reduce them to something ordinary. There were no Devil Fruit users in the Naruto world. He had made a note of that and moved on, treating the absorption property as simply inapplicable to his current circumstances.
But chakra was this world's version of that power. It was the fundamental energy that every technique in this world was built on. And the Dark-Dark Fruit, which had been slowly adapting to this world's laws alongside everything else about him, had apparently updated its understanding of what it was supposed to absorb.
When he had sparred with Kakuzu, there had been no such effect. The fruit hadn't touched his chakra. But that had been months ago, before the assimilation had progressed to its current stage. Something had shifted in the interval.
"Is there a problem?" Kakuzu asked.
Finn shook his head. "No. Give me five minutes."
Neither Kakuzu nor Sasori argued with this. Sasori's tone had shifted in a way Finn noticed but didn't comment on: the question had been practical, the initiative handed over without posturing. Something about the last ten minutes had completed a calculation Sasori had been running since their first encounter.
Finn waited. Inside the sphere, the darkness worked methodically through the Susanoo's structure, pulling chakra out of the compressed space and drawing it inward along channels Finn could feel but not fully describe. After five or six minutes, he released the Gravity Domain. The stone sphere crumbled. Uchiha Kagami lay in the clearing, unconscious, his chakra network effectively empty.
A ninja without chakra was a different category of problem than a ninja with it. The body still had its conditioning, its instincts, its accumulated physical training. But the toolkit that made a shinobi genuinely dangerous was chakra-dependent almost entirely. Without it, Kagami was a skilled, well-built man in his middle years with no particular advantage over anyone else in his weight class.
"Uchiha," Sasori said, looking down at him with the flat assessment he gave most things. "Not so impressive now."
"Without Finn, you weren't his match," Kakuzu said.
Sasori produced a small needle from his sleeve, bent over Kagami, and administered the injection with practiced efficiency. The liquid was green, which did not suggest anything comfortable about its mechanism.
"Without my antidote, he won't be condensing chakra when he wakes up," Sasori said, straightening. He bent and lifted Kagami by the shoulder, settling the unconscious man across his back. "He'll be useless. We should move before someone comes looking." He glanced at Finn and Kakuzu. "Where are you two heading?"
"The Bear Country Exchange is still operational," Finn said. "Though I'm not in a hurry to get back to it."
"I haven't had a fixed residence in thirty years," Kakuzu said. "I go where the work is."
Sasori considered this for a moment. "I have a base in the Land of Birds. Come there first. The Bird Country sits between Wind and Earth; the war's running through it. There's no shortage of work for either of your preferred activities."
Kakuzu's interest registered visibly. Corpse acquisition and mercenary contract work in an active war zone was, from his professional perspective, a favorable operating environment.
Finn looked at Sasori with mild amusement. "You're inviting us to your secret base. Does that mean you've thought about the proposal?"
A pause. Sasori looked at the middle distance. "I can't think of a reason to refuse right now."
"Good enough," Finn said, and meant it. He wasn't interested in manufactured enthusiasm. This was better: a practical man doing a practical calculation and arriving at a practical answer.
They left the clearing. Behind them, the bodies of both Konoha and Cloud shinobi lay sealed in Kakuzu's scrolls or still pressed into the dark-stained earth where the Abyss of Darkness had held them. When Konoha's support troops reached the battlefield half a day later, they found the vanguard position empty. No Kagami. No survivors from either side. Evidence of a significant engagement but no explanation for who had been responsible for the final state of it.
The obvious assumption was the Hidden Cloud. When the Cloud's own reinforcements arrived shortly after and found Konoha troops moving through the area, they drew the same conclusion in reverse. Both sides spent the next several days blaming each other for something that neither of them had done, which was, all things considered, the cleanest possible outcome for everyone who had actually been responsible.
The three of them moved south and west, cutting through the Land of Fire rather than around it because they were skilled enough to make that the path of least resistance. Carrying an unconscious Uchiha clansman through Konoha's home territory was a certain kind of arrogance, but arrogance backed by sufficient capability tended not to produce consequences. They passed through without incident.
Finn had been thinking about the scale of this world ever since he arrived. The ninja world was physically smaller than the One Piece world in ways that kept surprising him. In the pirate world, half a month of sailing might not close the distance between two adjacent islands in the New World. Here, half a month of travel on foot across multiple national borders was more than sufficient to reach almost any destination he could name. The five major countries and all the small nations between them occupied a landmass that a Marine warship could have circumnavigated in a season.
Dense world. Everything compressed into a smaller space, which meant the interactions between powers, the collisions and alliances and betrayals, all happened faster and with less distance between them.
Just over ten days of travel brought them into the Land of Rain.
The Rain Country lived up to its name. It was always raining. Not heavily, not in a way that disrupted movement, but constantly, a fine persistent mist that soaked into everything over time and made the landscape feel permanently gray. The architecture had adapted: broad eaves, drainage channels built into every surface, stone roads that ran slightly crowned to shed water to either side. The country had been fighting someone else's war for longer than most of its current population had been alive, and it showed in the way the buildings were maintained: functional, solid, not particularly invested in aesthetics beyond what function required.
They found a pavilion with a stone table and sat out of the immediate rain. At Sasori's feet, wrapped in cloth, Uchiha Kagami lay still. He had remained unconscious for the entire journey. Sasori had administered injections at regular intervals, and by some mechanism Finn did not fully understand, Kagami had gone the entire transit without needing food, water, or any other maintenance a living person normally required. He remained alive. Sasori had said, without particular affect, that he would stay alive as long as Sasori decided he should.
The map was spread on the stone table surface, weighted at the corners against the wind. Finn had been studying the geography since they arrived, filling in the gaps in his mental model of how this part of the world was actually laid out relative to everything else he knew about it.
He found Kannabi Bridge.
He had known the name. He had known what it represented in the war's timeline: the battle that had broken Iwagakure's logistical spine, that had made Minato Namikaze's reputation as the defining figure of the conflict, that had cost Obito Uchiha everything and started a chain of events that would not fully resolve for decades. He had not known exactly where it was.
He looked at it on the map and thought about what he was actually seeing.
The bridge connected the Land of Birds to the Land of Rain. It was not in the Land of Grass, not near the Land of Waterfall, not anywhere he had placed it in his mental geography. It sat in a corridor between Wind Country and Earth Country that gave the bridge strategic value in two directions simultaneously: through the Land of Rain toward Konoha from the northwest, and back through the Land of Birds toward the Wind Country's flank. Iwagakure had been using it as the logistical artery for a two-front war. Taking it hadn't just damaged their position against Konoha; it had compromised their ability to sustain pressure on the Wind Country at the same time.
And Sasori's secret base in the Land of Birds was not far from Kannabi Bridge's position on the map.
Finn looked up from the map. He looked at Sasori. He looked back at the map. He looked at the approximate position of what he knew about Uchiha Madara's long-term operational base, the place where an ancient man had spent decades in isolation maintaining the infrastructure of a plan that had been running since before the founding of the hidden villages.
He looked at Sasori again.
"Are you living next door to Uchiha Madara?"