Chapter 39: Flying Thunder God Technique
After "reluctantly" accepting the Third Hokage's reward, Nan took the mission scroll and respectfully bid farewell.
Shizune was expected to return in two days, so he decided to treat this short break as a vacation. It also gave him time to study the powerful jutsu the Third Hokage had just given him—maybe he could even master it early.
Originally, Nan had turned down Sarutobi's rewards in hopes of negotiating for something greater. To his surprise, the old man had been so impressed by him that he granted him access to a technique from the Sealed Scroll of Forbidden Jutsu.
When it came to choosing a technique, Nan had put serious thought into it.
The scroll contained many high-level jutsu, but only a few were truly useful to him.
Nan was already an all-rounder ninja, especially after unlocking the Mangekyō Sharingan. With four Mangekyō abilities, he was confident that even against someone like Nagato with the Rinnegan, he could come out on top.
He mentally reviewed his current capabilities. Taijutsu wasn't a priority—there weren't any relevant techniques in the scroll anyway.
As for genjutsu, he needed it even less. The only notable illusion technique listed was "Bringer of Darkness", which was slightly better than the standard three-tomoe illusions—but barely.
Once he activated the Mangekyō, Nan could likely control even Tailed Beasts with his illusions. So genjutsu was effectively covered.
He flipped through the index Sarutobi had given him, though it was clear the list was incomplete. Some jutsu Nan knew of—like Reaper Death Seal and Edo Tensei—were absent.
That made sense. These techniques were both forbidden and dangerous, and the village had no intention of letting anyone learn them again. Keeping them hidden from Nan was expected.
Still, if he could pick any jutsu, Edo Tensei would've been his top choice. It was perfect for someone like him—summoning an army of immortal corpses and commanding them from the rear suited his cautious nature perfectly.
But since Edo Tensei wasn't an option, the next best thing was the legendary Flying Thunder God Technique.
Sure, it required him to be on the battlefield in person, but the ability to teleport instantly made it one of the best "hit-and-run" jutsu ever conceived—exactly the kind of tactical advantage Nan loved.
In fact, among the techniques the Third had offered, only "Bringer of Darkness " and "Flying Thunder God" were truly high-level. This wasn't a coincidence.
Sarutobi was clearly trying to groom Nan for the Hokage path, which is why he gave him access to two jutsu created by the Second Hokage. Until now, the only other person who had received such a privilege was Namikaze Minato.
The Third had heard that Nan was highly skilled in genjutsu, capable of hypnotizing people with his Sharingan before performing delicate surgeries. He fully expected Nan to choose "Bringer of Darkness ", the most advanced illusion technique available.
To his surprise, Nan chose Flying Thunder God instead.
Coincidentally, Nan's upcoming mission partner, Minato, already mastered the jutsu—so it would be the perfect opportunity for Minato to pass on some experience.
If Nan could truly master Flying Thunder God, Konoha would gain another user of one of the most powerful teleportation jutsu ever created.
Nan returned home with the scroll, recalling the Hokage's strict instructions: read it once, then destroy it. Under no circumstances could this technique be leaked.
Understanding the gravity of the situation, Nan activated his Sharingan and instantly memorized the entire scroll. He didn't even bother reading through the contents yet—he would review it later. With the knowledge secured in his mind, he used Fire Style to incinerate the scroll until nothing remained.
Once he began recalling the technique's contents, he realized just how incredibly complex it was.
It wasn't like Shadow Clone Jutsu, which only required large amounts of chakra—something even someone like Naruto could pick up instantly.
Flying Thunder God was fundamentally different from traditional ninjutsu, which typically just required chakra nature manipulation and hand signs.
What made this jutsu so difficult was its deep reliance on scientific principles, especially the structure of space itself. That's why, even in the original timeline, so few ever learned it.
To master the Flying Thunder God Technique, one had to understand the concept of spatial constructs. But in this world, ninja academies only offered a three-year basic education. Where would a typical ninja even gain the knowledge required to grasp something this advanced?
Nan had no idea how Minato had managed to learn this technique—let alone how the Second Hokage had even invented it.
Space-time required concepts from quantum physics to explain. Even in his previous world, it was a science still in its exploratory stages.
The invention of the Flying Thunder God Technique didn't mean that the shinobi world's quantum mechanics were more advanced. Rather, it was the existence of chakra—a mysterious force that seemed to act as an entirely new kind of sense, one that allowed perception of spatial structures.
It was likely that the Second Hokage had simply stumbled upon this property by accident and had the genius to turn it into a technique.
After reviewing the entire scroll mentally, Nan let out a sigh of relief. He had worried he might not be talented enough to learn this technique, but now he was confident—his odds were actually pretty high.
The Flying Thunder God had many requirements:
Innate sensitivity to space (a natural talent for space-time jutsu)
Strong chakra reserves
Superb chakra control
And a deep understanding of spatial structure
As it turned out, Nan checked every single box.
First, his chakra reserves had grown significantly in recent times—already exceeding those of most elite jonin.
And in terms of chakra control, he might very well be one of the best in the entire shinobi world.
He could even summon a clone from any location directly to his side—clearly an example of spatial manipulation, which proved he had a natural affinity for space-time ninjutsu.
As for understanding spatial theory? Nan dared say that his past-life knowledge of physics gave him a better grasp of the concept than anyone in the shinobi world.
In fact, the more he thought about it, the more he realized—Flying Thunder God might be a perfect fit for him. Even more than the Third Hokage realized... perhaps even more than the technique's creator, the Second Hokage, could have imagined.
If all went well, Nan could probably master the Flying Thunder God Technique to the level of the Fourth Hokage, maybe even faster and more effectively than Tobirama himself.
It really was kind of tragic when you thought about it—the Second Hokage went through all the trouble to create the technique, yet barely used it himself. In the end, it was others who elevated it to legendary status...
After finishing the scroll, Nan couldn't wait any longer—he was dying to start training.
He headed to a training ground he'd used before and activated a method he hadn't employed in a long time—his Shadow Clone Training Method. He immediately created ten clones to begin intensive practice with the Flying Thunder God.
Lately, he had been using shadow clones for healing and surgeries, so his understanding of clone mechanics had reached a new level. He now knew how to conserve chakra more efficiently.
Creating ten clones for training was no longer a burden at all.
Following the scroll's instructions, Nan focused on sensing the force of space-time.
Combining his past-life knowledge of physics with his own theories on chakra behavior, he believed it wouldn't take long before he could truly perceive space-time.
And he was right.
With the help of his clones, it took less than one afternoon for Nan to sense the spatial forces. He had just completed the most critical step in mastering the Flying Thunder God Technique.
He then had one of his clones head off into the distance and leave a Flying Thunder God mark using space-time chakra.
Now it was time to test whether he could actually teleport to it.
Nan extended his senses, locked onto the mark, and tried to activate the technique.
But just before making the jump, a thought crossed his mind—what if it failed? Who knew what kind of backlash might result?
To play it safe, he quickly created another shadow clone and told it to attempt the teleportation first.
The clone followed the instructions from the scroll precisely and activated the Flying Thunder God Technique.
With a soft whoosh, the clone instantly appeared at the marked location.
Nan's eyes widened in disbelief.
It worked! The Flying Thunder God had worked! He jumped up in excitement.
But then, he noticed something strange—the clone who had teleported suddenly collapsed to the ground, retching violently.
And then—poof—the clone vanished.
The feedback hit Nan instantly. A wave of overwhelming dizziness crashed over him, leaving him stunned.