Outer Path Jade

Uesugi Shinji naturally had no idea about the strategic policies laid down by Kirigakure's higher-ups, as he was far away, operating within the Land of Hot Water. At that moment, he was in a forest, testing a jutsu he was developing—a jutsu he had high hopes for, believing it could help him break through his current bottleneck in strength.

Half a year earlier, Uesugi Shinji had noticed that his progress was slowing more and more. Clearly, his strength was approaching the limit of what his body's natural talent could achieve.

Even if he trained diligently for years to come, the strength he could gain would be extremely limited. As he grew older, his strength might even begin to decline.

Although Uesugi Shinji couldn't imagine just how powerful the various prodigies would be during the Fourth Shinobi World War, even his current knowledge told him that the limits of humanity in this world were nowhere near what he had reached.

For someone who pursued strength, stagnation and decline were unacceptable.

Chakra was the foundation of a shinobi, so the most direct way for one to grow stronger was to increase their chakra. If he could raise his chakra reserves to Kisame's level, his combat strength could increase four or five times over!

For shinobi skilled in chakra control, increasing their chakra reserves didn't simply mean having a longer "mana bar." Properly used, chakra could improve a shinobi's strength, speed, and the power of their ninjutsu and genjutsu across the board.

It was just that most shinobi weren't particularly skilled at using chakra. And among those who were, most had limited reserves, so they had to ration their chakra carefully in actual combat.

Uesugi Shinji had been searching for a way to increase his chakra reserves. He had conducted extensive research and experiments, and his partner, Kisame, had also volunteered to take part at his request.

Of course, Kisame's role in the process was to be studied.

Fortunately, Kisame, who was born with astonishing chakra reserves, had been willing to help. In the end, Uesugi Shinji found a formula that could replicate the chakra condensation within Kisame's body and successfully developed a sealing jutsu that could theoretically increase a shinobi's chakra reserves by a great deal: the Outer Path Jade Seal!

In the center of a clearing, four enormous scrolls lay neatly spread out. Each was covered in intricate sealing formulae, and together they formed an even more complex sealing array.

Uesugi Shinji stood at the center of the array, performing Hand Seals at a steady pace. He wasn't in the middle of a battle, so there was no need to make the seals as quickly as possible. He only needed to maintain a normal pace and complete each seal accurately and smoothly.

Not far outside the sealing array, Kisame watched it with bored incomprehension. Though he wasn't a shinobi skilled in sealing jutsu, even he was awestruck by the array Uesugi Shinji had created.

Before this, he had never seen a sealing array this complex—or even heard of one.

What Kisame didn't know was that Uesugi Shinji had a Light Brain in his mind, a top-tier piece of technology from another world. It helped him perform calculations and analyses that ordinary people could never manage, making it far easier for him to develop jutsu than it was for an average shinobi.

Uesugi Shinji had already completed more than thirty Hand Seals. Combined with the intricate array beneath his feet, the sealing jutsu was among the most complex in the entire Shinobi World.

Gradually, pale blue light appeared across the formulae in the array. It was chakra without any elemental nature. When Uesugi Shinji formed the forty-ninth seal, the entire sequence of Hand Seals was complete.

All the formulae in the sealing array flared with light, and a vast amount of chakra surged out of them. It quickly gathered in the center of the array, forming a blue sphere of light about the size of a soccer ball. As more chakra flowed into it, the sphere slowly deepened from pale blue to dark blue, and its initially dazzling glow gradually dimmed.

This dark blue sphere of chakra was the Outer Path Jade that Uesugi Shinji had developed!

He had named the sealing jutsu the "Outer Path Jade" because its chakra was too powerful for a shinobi to absorb directly into their body. Instead, it could only hover beside its user like an "external attachment." The user could draw its chakra into their body and then put it to use.

Kisame stared at the Outer Path Jade hovering in midair, his eyes full of shock.

Though it still contained less chakra than Kisame himself, it held seven or eight times as much chakra as an ordinary jonin—including Uesugi Shinji.

Kisame's shock didn't last long. He soon regained his composure, then raised a hand to his chin and said to Uesugi Shinji, "Well, well. When we sparred before, my overwhelming chakra advantage let me beat you by a hair. But if you can really make that sphere's energy entirely your own, I'm afraid I won't stand a chance against you."

Uesugi Shinji didn't respond. All his attention was focused on the Outer Path Jade before him.

Only then did Kisame notice the bead-sized drops of sweat trickling down Uesugi Shinji's forehead. His expression had also grown increasingly grave.

Suddenly, blinding white light appeared across the Outer Path Jade's dark blue surface. The chakra rippled violently, sending wave after wave across the sphere. It was clearly extremely unstable, on the verge of bursting.