The Arena was opened once more, but this time the two did not fight, instead standing together.
Rias took out the Shinigami piece, and the Arena projected it perfectly.
"Let's test it first, see if there are any issues with the spiritual body."
Rias handed the sky-blue King Piece to Unohana Retsu.
"It's very beautiful. You've worked hard."
Unohana Retsu took the piece and chuckled lightly.
"It's just a normal transaction."
Rias's black tail swayed. The adorable little girl looked utterly endearing.
Especially with her serious expression, it made one want to kiss, hug, and lift her high~
Involuntarily, Unohana Retsu gently patted Rias's head.
"Hmm?"
Rias tilted her head, asking curiously, "What's wrong?"
"Well, Miss Rias is very cute."
Unohana Retsu praised, then casually withdrew her hand.
"Alright, let's get to the main task."
Rias urged, her eyes sparkling with anticipation.
"Mm."
Looking at Rias's cute expression, Unohana Retsu couldn't help but smile, then used the method Rias taught to fuse with the devil piece.
Soon, the piece fused into Unohana Retsu's spiritual body, then penetrated deep into her Reiryoku Core.
The so-called Reiryoku Core is the life energy of the soul, the source that generates spiritual pressure.
It is the spiritual pressure core possessed by a spiritual body, also the energy that sustains the spiritual body's life. If the Reiryoku Core leaves the spiritual body, that entity would die on the spot.
Therefore, the Reiryoku Core is extremely important.
Fortunately, the Reiryoku Core showed no issues.
The piece entered the Reiryoku Core, then resonated, and the piece also gained Unohana Retsu's imprint.
Compared to a Zanpakutō, the connection was even more intimate, and the piece seemed to become an extension of her will.
After complete fusion, all pieces including the King resonated. The pieces also gained an energy attribute, and Unohana Retsu's spiritual pressure began to surge dramatically.
Instead of the tenfold increase Rias had estimated, this King Piece increased her spiritual pressure by a full twenty times!
If she performed Bankai on this foundation, the increase might be much less, but this spiritual pressure had already completely surpassed that of the strongest Shinigami, Yamamoto Genryūsai Shigekuni!
However, if the two were to fight, Unohana Retsu might be at a significant disadvantage.
After all, Yamamoto Genryūsai Shigekuni possesses the strongest fire-type Zanpakutō, Ryujin Jakka.
This is a Zanpakutō that stands at the pinnacle of 'magical damage'. Aside from Zanpakutō like the Zero Squad Monk's which target names, it is basically an unsolvable weapon in the Shinigami world.
If Yamamoto Genryūsai Shigekuni has a weakness, it can only be his physical body.
Even if heart, skill, body, and spiritual pressure are all trained to their limits, it still cannot change the fact that his body is a weakness.
"It seems to have succeeded. I'll send the Shinigami piece to you later."
Rias nodded in satisfaction.
"What about you?"
Unohana Retsu asked, "How is the Asauchi?"
"Haven't had time to experiment yet."
Rias shook her head, then drew the Asauchi she was holding.
For Rias, this blade was simply too long.
Fortunately, an Asauchi undergoes some transformation after becoming a Zanpakutō, so Rias wouldn't have to carry such a large sword around every day.
Sitting cross-legged in the air, Rias deployed her Formula and began analyzing the Zanpakutō.
"Souls are the raw material."
Rias murmured to herself.
In the analysis of the Magic Formula, the raw material of this blade was a substance never seen before.
Although never seen, its characteristics were close to those of a soul.
This made Rias think of the Asauchi's description: the raw material for Zanpakutō, like the 'White Hollow' created by Aizen Sōsuke, is formed by fusing the souls of many Shinigami.
This made Rias feel a bit uncomfortable, but fortunately, after forging, the Asauchi had lost its attributes and personal imprints, washed clean into pure white.
After a brief analysis of the material, next was the manufacturing technique.
This was slightly more challenging. After briefly analyzing and understanding the composition of the Zanpakutō, Rias began experiments to form her own.
Rias infused Power of Destruction into the Asauchi. Soon, under her observation, she found the Power of Destruction naturally flowing within the Asauchi, as if refining it.
Simultaneously, the minimal special energy contained within the magic power was absorbed by the Asauchi.
The magic power itself bonded with the blade, and as the energy increased, the volume expanded.
Perhaps magic power also has an affinity with souls, which is why it can form the energy required for a Zanpakutō.
"The blade of a Zanpakutō will become massive as energy increases, so at this point, the Zanpakutō needs to be compressed."
Unohana Retsu said.
She remembered the original work also had this concept. It seemed to be about a Hollow's Shinigamification, then discussing the size of Zanpakutō with Shiba Isshin before being instantly killed.
"Compression, huh? Whether it's magic power or a blade, it seems concentration is indeed the essence."
Rias chuckled lightly, then began compressing the blade.
Soon, the Asauchi returned to its original size.
Simultaneously, a faint energy was absorbed, something Rias only discovered using her Formula for observation.
Although this energy was too faint for Rias to perceive directly, her Fusion Equation had already analyzed magic power to a certain degree, allowing her to realize what this energy was.
"To create your own Zanpakutō, you need to inscribe the essence of your own soul into the Asauchi."
Unohana Retsu had clearly realized this as well, but compared to Rias, she made this judgment based on a millennium of experience.
She looked at Rias and said, "A Shinigami's spiritual pressure contains a small amount of soul. This energy is the so-called 'essence.' I imagine Miss Rias's magic power is the same."
Not just spiritual pressure; in fact, things like blood and sweat also contain a small amount of soul.
The Vampires in No Game No Life can survive on just this small amount of soul~
This amount of soul is very minute, acting as a person's special imprint, containing their essence.
Because it's shed, a product like the body's natural metabolism, losing it has no impact.
Fortunately, since birth, Rias has always been enveloped in a layer of Power of Destruction. Any naturally metabolized product would be directly 'destroyed.'
Disgusting things like cloning wouldn't happen to her.
"I see."
Rias nodded. "Using the pure white soul within the Zanpakutō as a base, it absorbs the soul energy naturally dissipated by life, thereby assimilating the soul within the Zanpakutō, turning it into one's own subordinate."
"Is this why a Zanpakutō doesn't split one's own soul, causing soul damage, yet possesses its own soul, thoughts, and personality?"
Hearing this, Unohana Retsu couldn't help but look at Rias in surprise.
Had she already analyzed the Zanpakutō to this extent?
Truly remarkable.
"In that case, all I need to do is infuse a large amount of soul into my magic power, then pour it in."
Rias murmured.
Not the core soul, but an extension of the soul.
Controlling the faint energy flowing within her body, Rias poured her soul into the blade.
With active infusion, the blade changed after about an hour, forming into a Zanpakutō.
The originally overly long blade also became smaller than a wakizashi, just the right size for the three-year-old Rias to use as a weapon.
And this entire process was completely recorded by Rias's Formula.
"Amazing."
Unohana Retsu exclaimed in awe. "No matter how many times, it's astonishing. Even the most famous genius Shinigami in history needed a full year to accomplish this, yet you did it in just an hour."
"It's simply about being able to analyze all of one's own composition, then precisely control all the energy within the body."
Rias said nonchalantly.
"..."
Unohana Retsu said quietly, "Miss Rias, if you weren't so cute, you'd probably get beaten up~"
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