"Studying Sensory Ninjutsu, is it?"
Shinichi wasn't surprised by Kushina's plan. At the same time, he didn't dismiss Sensor Ninjutsu just because he had already mastered the Byakugan. As Kushina said, Sensor Ninjutsu and the Byakugan were fundamentally different.
The Byakugan offers a 360-degree, all-encompassing field of vision, and for those who have awakened it, their sight can even cover an area up to one kilometer away.
The viewing distance of every Hyūga's Byakugan varies, but generally falls within this range. Even Hyūga Shinichi's Byakugan can "only" cover a range of five kilometers at most. Furthermore, limited by the user's information processing ability, Byakugan users often need to concentrate intensely when scouting distant enemy positions. Limited range, but exceptionally high precision—that is the characteristic of the Byakugan's sensing.
However, the Sensor Ninjutsu Kushina spoke of was quite different. Sensor Ninjutsu typically focuses on sensing chakra as its primary target.
It cannot detect things that do not carry chakra, and its precision is nowhere near that of the Byakugan. Correspondingly, the range of Sensor Ninjutsu is much greater than the Byakugan's, though this also depends on the user's individual condition; not everyone can achieve an expansive sensory range.
The masters of Sensor Ninjutsu are the two Flying Thunder God users: the Second Hokage and the Fourth Hokage.
The Second Hokage's sensing ability was powerful; simply by touching the ground with his hand, he could accurately perceive the enemies' location, number, and even the general strength level of some individuals.
The Fourth Hokage's sensing ability was also terrifying, capable of perceiving the Fourth Great War battlefield from hundreds of kilometers away while sealed in the Reanimation Shrine.
The typical features of Sensor Ninjutsu are its strong focus—targeting individuals with chakra and its vast range.
For the Flying Thunder God Technique, the caster needs to sense the location of their mark. In this regard, the Byakugan's ability is relatively weak, as there is no time in battle to carefully search for the marked location within the visual range! But Sensor Ninjutsu is different; once the user senses their own chakra mark, they can immediately perform a spatial jump.
The Byakugan and Sensor Ninjutsu are, after all, two separate systems. In this area, even Minato's teacher, Jiraiya, was far inferior to Minato.
Jiraiya needed to actively use techniques like the Barrier: Toad Gourd Prison to sense enemy locations, whereas Minato could sense enemies without even performing a hand seal. Many ninjas who failed to master the Flying Thunder God Technique did so because they lacked the talent for Sensor Ninjutsu.
The Uzumaki Clan's secret Sensor Technique is the Mind's Eye of the Kagura (Kagura Shingan), capable of easily covering a range of ten kilometers.
"Sensor Ninjutsu is also called Enemy Sensing Jutsu."
"Simply put, it's about sensing different types of chakra."
"Whether it's the enemy's or your own, you need to sense and distinguish these chakras."
"The technique I'm about to teach you is called the Mind's Eye of the Kagura."
"It involves integrating your own chakra into the air to expand your sensory domain."
"How far you can sense depends on individual ability."
"I'll teach you the hand seals. First, perform the technique and try to feel it."
Under Kushina's instruction, Shinichi began training the Mind's Eye of the Kagura. Before this, he thought the Mind's Eye of the Kagura was a bloodline limit unique to the Uzumaki Clan, but now it seemed to be a secret technique at most, not a bloodline limit.
Moreover, the jutsu's execution method was unique. Unlike Nagato's Sensor Ninjutsu, the Tears of the Fierce Water (Rain Tiger at Will Technique), this jutsu combined chakra with air to boost the sensory range. Nagato's technique, on the other hand, combined chakra with rain, allowing him to sense everything within the raining parts of the Land of Rain.
Understanding the basic principle of Sensor Ninjutsu, Shinichi could roughly grasp why Tobirama could sense enemy location and strength just by touching the ground with his hand.
The general principle must be similar, but the object combined with the chakra was slightly different, leading to varied effects for different techniques.
It was impossible to say which type of Sensor Ninjutsu was superior. The Mind's Eye of the Kagura would likely struggle to sense chakra fluctuations underground, and Tobirama's Sensor Ninjutsu would similarly have "blind spots." In terms of sheer precision, neither type could compare to the Byakugan.
But if the goal was to use the Flying Thunder God...
"The range of Sensor Ninjutsu often correlates positively with the caster's chakra reserves."
"The larger your chakra reserves, the wider your sensory range tends to be."
"I can sense that your chakra is immense, not even weaker than mine."
"Calling you a Tailless Tailed Beast wouldn't be an exaggeration. If you can master the Mind's Eye of the Kagura, your sensory range, once proficient, shouldn't be much smaller than mine."
Kushina was using "encouragement-based education." While teaching Shinichi to release his chakra and combine it with the air, she was also sensing Shinichi's chakra.
Shinichi now sat with his eyes closed, performing a single hand seal to help release his chakra.
After an unknown amount of time, a bright spot suddenly appeared in the inner vision of darkness and chaos as he kept his eyes closed.
This bright spot felt incredibly powerful and very warm to Shinichi. As he sensed it closely, a turbulent, violent aura emanated from the depths of the bright spot, causing Shinichi's body to tremble involuntarily before he quickly opened his eyes.
Simultaneously, within Uzumaki Kushina's body, the Nine-Tails, which had been dormant, suddenly opened its eyes. Its body was securely bound by chains made of sealing jutsu, and sealing stakes pinned its tails and body to a rock sphere.
The moment it awoke, the Nine-Tails roared fiercely within the sealing space. The terrifying gust of wind shook the sealed space.
Kushina, sitting next to Shinichi, seemed to sense something. She frowned slightly and gently rubbed her lower abdomen. In the sealing space, golden chains shot out from the void, wrapping around the Nine-Tails' mouth. The roaring abruptly ceased, and the sealing space returned to silence.
Bloodshot eyes flared on the Nine-Tails' face; a visceral hatred surged within its heart. Freedom... freedom was an unreachable dream.
Outsiders only knew the Nine-Tails as the embodiment of "hatred and chakra." But how could humans understand that the Nine-Tails' hatred had accumulated daily in this dark, endless imprisonment? When the Sage of Six Paths divided the Ten-Tails and created the Tailed Beasts, Kurama was just a harmless, cute little fox.
He even shed small tears when saying goodbye to the Sage of Six Paths. But now, the hatred and violence contained within its chakra were powerful enough to influence its Jinchūriki.
Hyūga Shinichi snapped open his eyes, retreating from the internal landscape after sensing the emotion contained within the "bright spot." He looked at Kushina in front of him, his eyes wide with shock.
"Is that...."
Shinichi guessed what the bright spot in his inner vision was: it was Kushina's chakra. The repressed emotion emanating from the depths of the bright spot was likely...
"Oh?"
"Did you sense it?"
"That is the Tailed Beast—the Nine-Tails sealed inside my body!"
"Shinichi, after sensing that terrifying existence, are you afraid? Are you afraid of me... this monster..."
Kushina lowered her head, asking with a complicated expression. Looking up at the young Shinichi beside her, an imperceptible flicker of hope crossed Kushina's eyes.
"Am I afraid? A little."
Hearing this, Kushina's eyes darkened, but only for a moment.
"But I'm afraid of the Tailed Beast, not Sensei Kushina."
"The Tailed Beast is the Tailed Beast, and Sensei Kushina is Sensei Kushina."
"You are not a monster, and I am not afraid of you."
Hyūga Shinichi smiled brightly and spoke sincerely.
Hearing his words, Kushina suddenly laughed: "I thought so too."
Then, Kushina murmured:
"I think my child in the future... won't be afraid of his mother either, will he..."
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