As everyone knows, life energy is a manifestation of Yang Release.
When Seimei infused Yang Release chakra into the severed arm, the Hashirama cells rich in life energy within it immediately reacted.
It was as if they had come to life, greedily devouring his chakra.
However, the overly active life energy also triggered the latent power hidden within these cells—the legendary Wood Release.
As a transmigrator, Seimei naturally understood that Wood Release wasn't as special as the legends made it out to be.
Like any other Kekkei Genkai formed by the fusion of two chakra nature transformations, it was rare but reproducible—provided one had the necessary aptitude.
The reason people held it in such high regard was simply because of who used it.
In other words, it was the "God of Shinobi" Senju Hashirama who made Wood Release famous—not the other way around.
Without the legendary Sage Body and near-infinite chakra, even Wood Release would only yield results similar to those of Yamato in later generations—or possibly even weaker.
After all, Yamato's body still contained a portion of Hashirama cells, making him more gifted than the average person.
Ordinary people, even if they mastered the fusion of Water and Earth Release, would likely produce only a pale imitation of Wood Release's power.
That said, ordinary people didn't have the capability to pull this off in the first place.
Compared to the total population of shinobi, those who could fuse two chakra nature transformations to create a Kekkei Genkai were incredibly rare—one in ten thousand wouldn't be an exaggeration.
Even fewer would happen to master both Water and Earth Release and then successfully create Wood Release. The odds were astronomically low.
It was perfectly normal that no one had replicated Wood Release for decades.
Pulling his thoughts back to the present, Seimei refocused on the severed arm.
Small, tender branches had begun to sprout from beneath the skin, swaying and growing like real plants.
Even with his mastery of supernatural powers, Seimei couldn't help but marvel at the sight.
After all, transforming flesh and blood into plant life defied not only the laws of physics from his previous life but was also considered miraculous even in the supernatural world of the ninja realm.
But if it existed, there had to be a reason for it.
Right now, he neither had the time nor the ability to delve into the deeper logic behind it.
For now, his priority was extracting the Hashirama cells to prepare for future assimilation.
With that in mind, Seimei stopped overthinking and began carefully channeling his Yang Release chakra into the severed arm, sensing the Hashirama cells within.
Minute by minute, he gradually familiarized himself with the cells' state and their subtle changes under various conditions.
After more than half an hour, Seimei withdrew his hand.
The preliminary work was done. Now it was time for the real extraction.
If Orochimaru were here, he would have pulled out countless scientific instruments to complete the procedure.
But Seimei couldn't.
Although he had been a university student in his previous life, his major had nothing to do with biology.
Even if it had, the anatomical differences between the two worlds would render much of his knowledge irrelevant.
So, he had to forge a different path.
With that thought, Seimei retrieved a stack of blank scrolls from his home.
He selected one and spread it out on the floor.
After a moment of contemplation, he began sketching and writing on the scroll.
While he lacked scientific methods, he possessed profound knowledge of medical ninjutsu and sealing techniques.
By combining the two, he could create an energy conversion array that would transfer energy from other cells into the Hashirama cells, using their subtle differences as the basis for separation.
As the process progressed, the other cells would wither and die from energy loss, while the Hashirama cells would be nourished, maintaining maximum vitality.
By the end, only the desired Hashirama cells would remain.
However, distinguishing Hashirama cells from others with precision was no easy task.
Fortunately, Seimei had just meticulously studied their differences and was confident he could create a sealing array with the necessary accuracy.
Time passed by slowly.
Night fell without Seimei even noticing as he repeatedly refined the sealing array and tested its effectiveness.
After more than ten hours of effort, he finally succeeded.
Seimei watched as a severed finger slowly disappeared within the sealing array. He picked up a glass vial on the other side of the array and swirled the pale green nutrient solution inside.
Injecting a bit of Yang Release chakra, he observed a small green sprout rapidly grow within the vial, draining the nutrient solution dry before shattering the glass.
The sound of breaking glass echoed through the room.
But Seimei paid it no mind.
Brushing off the shards from his hand, he grinned, feeling his hard work had finally paid off.
Without hesitation, he placed the remaining severed arm onto the sealing array, set up another vial of nutrient solution, and activated the array once more.
This time, the array took longer due to the larger volume of material.
Several minutes later, the array completed its operation.
Seimei carefully picked up the vial.
There was no need to test it—he could feel the vibrant life force within.
Previously, the sparse number of Hashirama cells made them difficult to detect.
But now that all remaining Hashirama cells had been gathered into one vial, their life force was palpable.
"Phew…"
Exhaling deeply, Seimei sealed the precious vial inside a specially made scroll using a storage seal.
Only then did he finally relax.
As soon as he let his guard down, exhaustion swept over him.