Returning to the mansion after meeting Mira, Azrael made his way straight to the bathroom.
He filled the bathtub with warm water and took out around fifteen different kinds of materials from his inventory.
There were blocks of various metals, herbs, a bottle of potion, and even a few rocks brimming with energy.
These were the items required to practice the Unyielding Body.
Oliver had delivered them the very next day after Azrael had embedded his substance.
Unlike ordinary defensive skills, the Unyielding Body was more like a body-refining art that directly strengthened the physical body itself.
To cultivate this skill, the user had to absorb the energies of specific materials and channel them into the body in the precise way described in the technique, thereby tempering the body.
However, this process was anything but easy.
There were two main reasons why the receptionist at the skill library had advised Azrael to choose another skill instead of the Unyielding Body.
The first and most important reason was that cultivating this skill was extremely painful.
Painful to such an extent that, among those who had attempted it in the past, some had lost control of the energy during the absorption process and ended up severely injured, while others had even lost their lives.
The second reason was the sheer cost of practicing this skill.
The Unyielding Body consisted of nine stages, and the materials Azrael had asked Oliver to prepare were just barely enough to step into the entry level—the first stage.
The cost of these materials alone exceeded one million cosmic energy stones.
Just reaching the first stage required over a million cosmic energy stones. By the third stage, which is the middle level of skill, costs soared into few millions, and by the ninth stage, which is perfection level, the price would exceed a hundred million.
(A/N: The mastery levels of skills, if forgotten, are: Entry Level → Middle Level → High Level → Peak Level → Perfection.)
In short, reaching perfection in this skill would demand an investment of over one hundred million cosmic energy stones.
And that was without even mentioning the hellish pain the user would have to endure throughout the process.
As such, the Unyielding Body was infamous among low-level skills, and very few people ever dared to practice it.
Of course, there were similar alternatives, such as the Primal Flesh skill which the receptionist had originally recommended to him.
That skill was not very painful to cultivate, and the cost of its materials was relatively low.
However, the drawback was that its effectiveness was far inferior to the Unyielding Body.
Azrael was not someone who liked wasting the money his parents had earned.
For example, he had refused to use the teleportation formation to travel to the Flato Solar System, as it was an unnecessary extravagance when a spaceship could take him there for far less.
But when it came to his own growth, he had no qualms about spending money.
Thus, he had chosen the Unyielding Body without hesitation.
He was also fully aware that the pain from cultivating this skill was no joke and could easily exceed his natural tolerance.
But with his Cold-Blooded trait, he could ignore pain almost entirely, so he was confident he could manage.
Once the bathtub was filled with warm water, Azrael picked up three blocks of metals—Soul Iron, Stormsteel, and Oblivium, all of which were brimming with the energy of the metal element.
He tossed them into the water before adding the Petra Shard and Terrastone, both rich in earth energy.
Then came the Deepmarrow Coral, Galeiron, and Voltcrystal, each carrying unique elemental forces.
Finally, he picked up a small bottle of light-green potion and poured it into the tub.
The instant the potion mixed with the water, the temperature rose, causing it to boil violently, and the water turned a mossy green.
The materials dissolved into pure particles of energy, bubbling furiously as their essence was released.
The last items were a bundle of herbs, which Azrael threw in as well.
The herbs withered the moment they touched the bubbling green water, their energy instantly absorbed and cooling down the water temperature.
Staring at the cauldron-like bath that now resembled a potion brewed by some evil witch, Azrael gulped nervously.
But knowing that the energy would soon begin to dissipate, he wasted no time.
He quickly stripped off his clothes and submerged himself in the bath.
At first, as his body soaked in the water, he felt only warmth—a soothing, comfortable sensation, like soaking in a hot spring.
But the moment he began channeling the energy according to the method described in the Unyielding Body, his expression contorted in pain, and even he couldn't help but draw in a sharp breath of cold air.
The energy pierced into every muscle fiber, drilling into his bone marrow.
It felt as if molten magma had been poured directly into his bloodstream, while thousands of scorching needles stabbed at his bones all at once.
"F*ck… it's a lot more painful than I thought…" Azrael gritted his teeth as the searing energy raged through his body, tempering his physique with merciless intensity.
Immediately, his Cold-Blooded trait activated on its own, numbing his mind to the agony.
Yet, even though his mind no longer registered pain, his trembling body betrayed the truth as ignoring pain didn't mean the body itself was unharmed.
Though his physique was being refined and strengthened with every passing second, his limbs quivered violently, and he found it difficult to even lift his hand.
'No wonder the receptionist and even Mom told me to choose another skill. This is only the first stage, and the pain is already beyond comprehension…' Azrael thought coldly, his expression indifferent under the trait's effect as he closed his eyes.
Time trickled by, and with every hour, the torment intensified.
The energy within the water gradually thinned as Azrael absorbed it, until—after nearly ten grueling hours, he lay sprawled on his back in the tub, staring blankly at the ceiling with an emotionless face.
(You have reached Entry Level in the Unyielding Body.)
Azrael glanced at the notification without moving, silently looking at it.
He could clearly feel his body had grown far stronger than before, yet at the same time, he was utterly exhausted, without the strength to move even a single finger.
'Now I understand why some people died attempting this skill…' He sighed inwardly, before opening his status window to check his condition.