Inner Ice Release

After understanding the situation regarding Hozuki Mangetsu's integration of Ice Release chakra, Uesugi Shinji continued his own training.

To Uesugi Shinji, this disciple Hozuki Mangetsu was merely a condition for his cooperation with Terumi Mei; he could not afford to invest too much energy into the man.

More importantly, he had made a major discovery during a recent skirmish with Namikaze Minato, providing a new direction for someone whose strength growth had hit a bottleneck.

The key to this major discovery was none other than Namikaze Minato's summoning beast, Gamabunta!

As a core member of Mount Myoboku, one of the three great sage regions of the ninja world, Gamabunta had learned how to use natural energy in combat since birth. This was the primary distinction between the beasts of the three great sage regions and other summoned creatures.

Gamabunta constantly maintained a large amount of natural energy within his body, and when performing ninjutsu, he would fuse this natural energy with his chakra to unleash far greater power.

However, natural energy is colorless and formless; normal ninjas cannot detect it at all, making the method of utilizing it a top-secret of the three great sage regions.

But for Uesugi Shinji, who possessed a Light Brain, he had actually discovered the omnipresent natural energy in the air long ago.

The air in the ninja world contains oxygen, nitrogen, natural energy, and other substances. Uesugi Shinji had never paid attention to natural energy before, not until he saw Gamabunta absorbing it from the air to replenish himself and fusing it into his chakra to launch powerful ninjutsu.

This discovery left Uesugi Shinji inwardly thrilled. During the time he spent guiding Hozuki Mangetsu in Ice Release training, he had been attempting to utilize natural energy himself, and he was now only a step away from success!

Standing on the surface of a clear, calm lake, Uesugi Shinji closed his eyes slightly, sensing the surrounding natural energy and slowly drawing it into his body.

He did not know that the substance he was absorbing was called "natural energy," nor was he aware that his current practice was known in the traditions of the three great sage regions as "Sage Mode."

The first threshold of Sage Mode training is sensing the existence of natural energy. Of all the ninjas who have the opportunity to encounter Sage Mode training, over ninety percent are blocked by this very threshold.

However, Uesugi Shinji had passively discovered the natural energy in the air through his Light Brain shortly after arriving in the ninja world, so this threshold simply did not exist for him.

The second threshold concerns the balance between chakra and natural energy, and most practitioners who cross the first threshold perish before this one.

The process of Sage Mode training is extremely risky. Once a practitioner fails to grasp the balance between chakra and natural energy, allowing the natural energy within the body to exceed their own chakra reserves, the body is eroded by the natural energy, triggering a series of malignant changes.

These changes are related to the surrounding environment and the practitioner's own chakra nature. For example, in Mount Myoboku, the consequence of the body being eroded by natural energy is petrification.

If in Shikkotsu Forest, excessive absorption of natural energy causes the body to wither like dead wood.

Training in Sage Mode at Ryūchi Cave is the most dangerous; once natural energy spirals out of control, the body rapidly rots. The venomous snakes of Ryūchi Cave will not only fail to save the failing practitioner but will instead swarm to devour them.

(Note: The effects of natural energy erosion in Shikkotsu Forest and Ryūchi Cave are invented by the author.)

Precisely because natural energy is extremely difficult to control and carries high risks, a necessary condition for ninjas to practice Sage Mode in the three great sage regions is possessing a sufficiently large amount of chakra.

The greater a ninja's own chakra reserves, the more natural energy the body can withstand, making the balance between the two energies simpler and naturally reducing the difficulty and risk of training.

Although Uesugi Shinji did not have a large amount of chakra, this second threshold was not a difficult problem for him either.

Because of the Light Brain's assistance, he could precisely control the balance between his internal chakra and natural energy. Overall, the principle was similar to how he fused wind and water chakra to create Ice Release chakra.

At this moment, Uesugi Shinji had completed the process of absorbing natural energy. A perfect balance between natural energy and chakra had formed within his body, and his physique gradually began to show some changes.

His originally jet-black hair and eyebrows gradually turned an icy white, and a diamond-shaped mark resembling an ice crystal appeared in the center of his forehead. The surface of the lake within a three-meter radius under his feet was frozen due to the influence of his Ice Release chakra.

This was Uesugi Shinji's own Sage Mode, which he called the "Inner Ice Release" state!

(Note: In Japanese, "Omote" (surface/outer) and "Ura" (inner/hidden) are used to describe appearance versus reality, or light versus dark.)

If any members of the three great sage regions were here now, they would be astonished to find that Uesugi Shinji's Sage Mode aura was stable and did not rely on any summoning beast that had mastered natural energy to maintain it. This was the final stage of Sage Mode—the Perfect Sage Mode.

Uesugi Shinji slowly opened his eyes, his pupils now the color of ice crystals. Even just looking into his eyes, one could feel a biting chill.

His hands moved rapidly through seals, and a large-scale Ice Release ninjutsu was completed in an instant.

"Inner Ice Release: Ice River."

A circle of white light instantly spread from the lake surface beneath his feet to the surroundings. In the blink of an eye, the entire surface of the lake was frozen over, looking like an incredibly smooth mirror when viewed from the air.

Seeing the effect of this ninjutsu, a flash of satisfaction crossed Uesugi Shinji's eyes.

After fusing with natural energy, the effect of the original ninjutsu had been greatly enhanced.

In his normal state, this ninjutsu would have taken at least five seconds to freeze the entire lake, and the temperature and strength of the ice would have been incomparable to what it was now.

Additionally, Uesugi Shinji could clearly feel that his current physical state was far superior to his usual self, showing that the "Inner Ice Release" state not only increased the power of his ninjutsu but also strengthened his taijutsu abilities.

"I really must thank the Yellow Flash. If it weren't for his summoning beast, I might have truly overlooked this omnipresent energy!"

After mastering the "Inner Ice Release" ability, Uesugi Shinji did not feel satisfied; instead, he felt an even greater longing for the "Outer Path Jade" sealing technique he had been researching.

Although the "Inner Ice Release" state was powerful, it could not solve his dilemma of insufficient chakra, and his endurance in battle remained a major weakness.

If he could complete the "Outer Path Jade" sealing technique, Uesugi Shinji believed his strength would surely be at the pinnacle of the ninja world, and perhaps he might even touch the realm of the legendary Senju Hashirama and Uchiha Madara.

"Next, I must find an opportunity to obtain a Tailed Beast. No, just a part of a Tailed Beast will be enough!"