"Simu-senpai, this is going too far! I'm afraid the entire Land of Wind is hunting me down right now!"
Tobi's tone was filled with dissatisfaction. In response, Simu simply shrugged with indifference. He didn't bother telling Tobi that the clone he used to impersonate him had already self-destructed right in front of Rasa. Instead, he said nonchalantly, "It's not like it's the first time. Just change your mask, Tobi."
"Simu-senpai really has a wicked sense of humor..."
Tobi stared at Simu's projection, seemingly trying to discern something from it. Unfortunately, the only things he could see were Simu's faint smile and the flat, impassive gaze hidden behind his glasses.
"Enough. Since you have successfully captured the One-Tail, bring it back as soon as possible to avoid any further complications."
Pain's intervention effectively ended the discussion. Simu knew that Pain was issuing an ultimatum. It had been over a month since the Hidden Sand Village incident, and Nagato had shown considerable respect as a partner by not pressing the matter until now. This was, after all, an obligation Simu owed in their partnership. He had no reason to refuse.
Pushing his glasses up slightly, Simu responded, "I understand. I'll head back soon."
"Good."
Pain nodded, and Simu's projection vanished instantly. His consciousness returned to the base.
"Sasori, we need to speed things up," Simu said suddenly while testing sealing jutsus with Sasori.
Sasori didn't ask questions. He simply nodded and said, "I understand. There shouldn't be any issues with this sealing jutsu anymore."
As the genius who created the Human Puppet technique, Sasori's proficiency in Yin-Yang Style and chakra control was exceptional. Although his knowledge of Sealing Jutsu was relatively average, he provided significant help to Simu throughout the research process. With Sasori's assistance and Simu's own knowledge, they finally mastered the technique Shukaku had taught them five days later.
Yin-Yang Seal.
The name made Simu think of the Yin and Yang duality from his previous life, as well as the Four Symbols and Eight Trigrams that stemmed from it. With the Sealing Jutsu mastered, it was time to put the plan into action. However, before officially sealing Shukaku, he needed to practice.
Back when Shukaku first handed over the technique, Simu had already prepared several experimental subjects. His method involved extracting Tailed Beast chakra and injecting it into the subjects to replace their original chakra. He then used a special method to fuse their souls with this chakra.
Evidently, not just anyone could withstand Tailed Beast chakra. Consequently, Simu performed physical modifications on these subjects, making them barely capable of carrying the power of a Tailed Beast. Of course, these subjects couldn't truly simulate Shukaku; they merely served as practice for Simu to hone the Sealing Jutsu.
Entering the laboratory, Simu snapped his fingers at the subjects confined inside. The subjects, previously submerged in Geninutusu, immediately began to riot. Tailed Beast chakra erupted from every pore of their bodies.
Had Simu not specifically modified their physical strength, they likely would have perished long ago from the erosion of the Tailed Beast chakra. Not everyone can endure such power, which is why various hidden villages must carefully select their Jinchuriki.
From Simu's current observations, the Uzumaki Clan remained the most suitable candidates for Jinchuriki. They possessed naturally powerful physiques capable of withstanding the erosion and mastered formidable Sealing Jutsu to suppress the Tailed Beasts, ensuring maximum stability. They were practically a clan built for the role of Jinchuriki.
As the subjects entered the first stage of Tailed Beast transformation, Simu finally began his first experiment. Concentrating his mind, he formed hand signs. His chakra rapidly transformed into dense rows of formulas that released from his body. These formulas acted like black chains, binding one of the subjects as a powerful sealing force erupted from them.
Next, following the method Shukaku taught, Simu made a grasping motion in the air. A chakra sword, burning like a flame, appeared in his hand.
A sealing sword condensed from Yang Style chakra.
He held the long sword and plunged it without hesitation into the monster-like subject covered in Tailed Beast chakra. An unparalleled sealing power bloomed, tearing the Yin Style chakra away from the Tailed Beast energy and merging it into the sword in Simu's hand.
Simu was actually quite surprised when he first saw this Sealing Jutsu. Using a sealing sword made of Yang Style chakra to tear—or rather, attract—the opponent's Yin Style chakra to achieve a split was a principle that mirrored the Yin-Yang theories of his past life. Combined with the name "Yin-Yang Seal," the connection was hard to ignore.
The function of Yin Style is "creating form from nothing," which simply means creating and shaping something out of a void. The function of Yang Style is "breathing life into form," injecting life into inanimate objects.
Essentially, a Tailed Beast is a mass of chakra composed of Yin and Yang. The Yin Style chakra is responsible for shaping the chakra into the Tailed Beast's current appearance, while the Yang Style chakra provides the life force, giving them a true, living consciousness. A Tailed Beast's consciousness and soul are born from Yang Style chakra, but once born, the soul represents Yin in a certain sense.
This is likely what they call 'Yang within Yin' and 'Yin within Yang'—the two generating each other and existing as one.
Simu reined in his thoughts. The Yang sealing sword in his hand had successfully sealed the Yin Style chakra from the subject. Immediately, a distorted, shadow-like Yin Style sealing sword appeared in his other hand. In the same manner, Simu sealed the subject's Yang Style chakra.
After multiple trials, Simu confirmed that this Sealing Jutsu was indeed viable. Of course, the scale of a Tailed Beast's chakra was vastly different from these subjects, and the difficulty of the seal would be worlds apart. Simu dared not be careless. He observed the two masses of different Tailed Beast chakra attributes he had sealed and recorded his findings.
Whether it is the Yang Style or Yin Style chakra, both contain a portion of the original soul. Once separated, these two chakra masses automatically form two new consciousnesses. Despite sharing the same source, these two consciousnesses will exhibit different personalities due to their different chakra attributes.