Luster

It didn't hurt, it just felt very nerve-racking, It was like watching your arm slowly shrivel up even though there was no pain. Yes...it was exactly that feeling.

Kai watched as his rocky body shed its crude exterior, a multi-colored glow could be seen from in between the cracks. Before long, his entire body had essentially "shed" its exterior, revealing a glowing, multi-colored gemstone in its place.

It had an enchanting luster that would capture the eyes of any person. Even those who disregarded gems would be fascinated by this beautiful piece and would be mesmerized by it. The gemstone no longer had its previous crude shape, it now had 2 large, sharp spikes jutting out with countless small spikes from a unseen center.

It reached roughly 50 centimeters in height and radiated a rainbow-colored light, lighting up most of the cave Kai was in. In short, it was breathtaking.

Kai snapped out of his daze, he was excited about the new change in his body, but he had to find out if anything had been damaged first. Which, to his delight, he could not find. It seemed that urge had allowed him to shed his body and... renew it? Kai wasn't sure what had happened but he was ecstatic regardless. 

Now my body ought to have some sort of boost right? I mean, look at my new body, it's breathtaking, It looks like some type of legendary material born once every thousand years. Little did Kai know how right he was.

The Ultimate Metal: Hihi'irokane. First discovered in one of the eastern continents, it is every blacksmith's dream to forge with this metal.

This metal is supreme in every way, it is insanely malleable, ductile, and a conductor of electricity, and most importantly, its magical conductivity is unbelievably high. The magical conductivity of a metal defines its value, with a high magical conductivity a metal can become many times stronger than its non-magical counterparts.

Using a highly conductive metal as the core of a staff, for example, can improve one's magic efficiency many times. The reason for this is that the mana is being contained by the metal, which results in the magic becoming much easier to control as it's in a contained space, instead of floating about in the air, less control will be needed to effectively utilize the mana.

The mana can then be shaped into the magic easier, which in turn reduces the amount of mana lost to the environment, as a result, a spell is formed faster or stronger. This is only one of many ways a highly magically conductive metal can be used, and that is only a highly magically conductive metal.

Now, what about The Ultimate Metal: Hihi'irokane? Well, let's just say that the 2nd most conductive metal is barely half as effective as it, and that metal - Tatanium - is only able to achieve a 48% magical efficiency.

Hihi'irokane has the affinity of every element, meaning a person can instill mana of any element into the metal and its mana conductivity would not decrease at all. These are only a few of the basic properties of Hihi'irokane that people have discovered since the metal is unfathomably rare and has not been discovered for more than half a millennia. 

Hihi'irokane is born from a long series of coincidences. A drop of liquid saturated with mana must pass through the natural mana of every element within a fraction of a second and must land on a metal ,and be instantly absorbed before the mana in the drop of water disperses.

This drop of water will gather at the center of the piece of metal and slowly gather the surrounding mana and grow, and once it has reached a certain threshold, the drop of mana can be "activated" by external forces, quickly transforming the insides of the metal into a multi-colored hue and shedding the remaining of the original metal.

Now, souls, on the other hand, are even more abstract. Once a person dies, the tiny soul is first hastily collected by ethereal winds, before... well, we don't need to say the rest since our protagonist has already evaded the first step.

However, the real kicker is that his soul was able to instinctively  navigate through the cracks between dimensions, evade countless threats between dimensions and space, and reach an entirely different world. Now, this would already be an unbelievable story but Kai, at the right time and right place, also happened to be directly on top of the metal that would soon become Hihi'irokane.

The drop of mana-saturated water landed directly on his small, tiny soul, bringing it into the metal as well. And, well, you know the rest. Calling this lucky was a severe understatement, considering that mana-rich locations, like the cave our protagonist is currently in, are deadly to unprotected souls; especially weak souls like his. Of course, our protagonist knows none of this right now

Kai immediately began experimenting with his new body. First, he tried to move it, which you can guess how it went, which of course is not. Kai expected this, considering he was now a big chunk of metal(?) gemstone(?). 

Guess I can't move huh? Kai realized something, he was trying to stand up as though he was a human even though he wasn't, Maybe he couldn't necessarily walk since he didn't have legs. Kinda stupid of me to try to walk as a rock... Kai thought as he tried to move one of his smaller spikes. Contrary to his expectations, it shook a little. Now we're getting somewhere Kai grinned in his mind.

Kai spent some time practicing moving singular spikes on his body. It didn't take him long before he was able to freely control one of his smaller spikes, he could even mold it into different shapes, which greatly shocked him. This... isn't this a bit OP? Kai was on cloud nine, Imagine what I could do with this, so far the shapes I've made have been simple but after I'd gotten the hang of it it was like second nature to me. Kai thought as he imagined himself instantly pulling out a blicky on some unfortunate enemies.

Just the thought of it made Kai giddy.