Mud to Stone

The first floor, in the stairwell, is where some miscellaneous items are piled up. It's rarely visited, making it quite suitable for a tunnel entrance.

Of course, he wouldn't openly lift the floorboards. Instead, he had Hei Bei dig a small hole leading underground, and then had Hei Bei start working from below.

"How's the efficiency?" Kamiya Keiyun asked from above.

"My claws are over ten times stronger than before! I can now do in a short while what used to take me all night!" Hei Bei said excitedly. "But where's the excavated dirt?"

"This..." Kamiya Keiyun thought for a moment. Right, this seems to be a problem!

Digging a hundred-meter-deep hole, which also needs to lead outside the village, would involve a considerable amount of earth, even if the tunnel wasn't too wide.

Kamiya Keiyun grabbed a handful of dirt, thought for a moment, and said, "Just pile it in the backyard for now. Tonight is just to test your digging speed! As for the dirt, I'll figure something out."

"Okay! And don't forget about the food you promised!"

"Of course not!" Kamiya Keiyun said with a smile, but as he smiled, he felt like crying.

Right, rats need to eat too!

Not to mention, after today, Hei Bei's two brothers and three sisters would also be coming.

One rat doesn't eat as much as a cat, but now there were six of them.

Especially since they had become Ninja Beasts, their appetites had increased!

"But it's a good thing roof rats are omnivores. Maybe I should find a grain merchant to cooperate with," Kamiya Keiyun mused. He realized he didn't even know who in the village dealt in grain!

In fact, because he had always stayed home before, he didn't know much about Konohagakure, nor did he understand its various political structures.

Waking up early in the morning, Kamiya Keiyun was astonished to see a pitch-black rat lying comfortably in Ruri's arms. The two little ones were sleeping soundly.

"Huh?" Kamiya Keiyun was surprised. This was okay? Weren't cats and mice natural enemies?

But then he thought about it. Even in his past life, pet cats usually wouldn't attack pet mice kept by their owners. Moreover, Ruri was now a cat that could talk and communicate with people.

Kamiya Keiyun put on his clothes and then tapped Hei Bei's head.

"What? I'm so sleepy!" Hei Bei said impatiently.

"Alright," Kamiya Keiyun nodded. After all, the little guy had worked all night, so he wouldn't disturb him.

He glanced at the backyard. Indeed, a considerable pile of dirt had already accumulated there, about a meter high.

When he went downstairs, Kamiya Koromo had already prepared breakfast. Seeing Kamiya Keiyun come down, she asked vigilantly, "Keiyun, didn't you bring back a cat earlier? Can it catch mice? I heard a mouse digging in the house last night!"

"Ah, Mom, don't worry about that," Kamiya Keiyun waved his hand. "I'll handle it. Oh, and don't worry about the dirt in the backyard either, I'll take care of it."

"Oh," Kamiya Koromo nodded. She didn't usually go to the backyard because it was shady, and they always dried clothes in the front yard.

"Indeed, there's also the issue of noise. I need to find a way to solve that too!"

After eating, Kamiya Keiyun took a roll of measuring tape and lay down in the stairwell, measuring downwards.

He marked a circle for Hei Bei, a circle with a diameter of 40 centimeters, and told him to dig down.

When he measured down, it was actually 2.5 meters deep!

"The formula for the volume of a cylinder is V=πr²h, so he dug out 3 cubic meters of dirt in one night!" Kamiya Keiyun was a little surprised. But then he thought, 3 cubic meters didn't seem like much!

After all, digging only 2.5 meters in one night meant it would take 40 days to reach 100 meters.

After 40 days, it would be too late!

Even if he called Hei Bei's entire family, it would only shorten the construction time to six days, and that was just for digging straight down. There was still the distance to dig from under Konohagakure to the outside!

"If only I could awaken a Minecraft System. A mere 100 meters would be done in less than a minute!" Kamiya Keiyun sighed, recalling how in Minecraft, dug-up dirt turned into small blocks and could be put into an inventory, eliminating the need for cleanup.

"Wait?" Kamiya Keiyun froze. Minecraft System, small blocks?

Kamiya Keiyun's mind began to race. He didn't have an inventory, but turning dirt into small blocks might not be impossible!

After all, he had discovered before that Chakra possessed both attractive and repulsive properties.

If he applied these two properties to dirt, shortening the distance between the dirt molecules, the volume of the dirt would naturally shrink significantly, thus solving the problem of where to pile it.

Kamiya Keiyun also speculated that digging itself shouldn't be too difficult, as it was Hei Bei's innate ability. A rat's son knows how to dig, right?

But transporting the dirt to the backyard would take a lot of time, especially for a single rat that couldn't use a cart. He could only move it bit by bit, and he might spend most of his time just transporting the dirt.

If there was a way to compress the dirt, the engineering speed could be greatly increased!

Kamiya Keiyun first went to the backyard, grabbed a large handful of dirt, and then headed to school.

Along the way, he began to experiment with his Chakra, bit by bit.

He condensed Chakra in his palm and then enveloped the dirt in his palm.

When the amount of Chakra was small, it exhibited an absorbing characteristic towards the dirt. When the amount of Chakra was large, it exhibited a repelling characteristic.

But now that the Chakra completely enveloped the dirt, this repulsive force had nowhere to go and could only be concentrated entirely on the dirt in his palm.

Then, the individual molecules constituting the dirt were compressed by the omnipresent Chakra, and naturally, they began to condense towards the center.

Trying bit by bit, working little by little, after researching all the way and then experimenting for two classes in the classroom, the handful of dirt that was originally the size of Kamiya Keiyun's fist turned into a black, stone-like substance about the size of an egg.

"It actually works! But the volume only shrunk by about a third, which isn't enough!" Kamiya Keiyun tossed the stone-like object in his hand. The density difference between stone and dirt isn't that large. If it only shrunk this much, he would still need to find a place to pile it.

At best, it would just change the pile of dirt into a pile of stones, but stones are too easy to notice. It would be better to just pile up dirt!

"But speaking of which, this level of control over Chakra feels less refined than using hand seals!" Kamiya Keiyun thought for a moment, then began to try forming hand seals to mobilize his Chakra.

He was already incredibly proficient with the twelve seals, and he knew that the twelve seals corresponded to various transformations of Chakra. Combined with the flow of Chakra he had just experienced, it wasn't difficult to deduce the seals from the results.

As expected, Kamiya Keiyun found that his control over Chakra's refinement increased significantly when he used hand seals.

If Kamiya Keiyun's control over Chakra was 1 when he first refined it, then after cultivating the Bright Virtue Method and starting to shape it into a human form, his control became 10. With the addition of his spirit and hand seals, his control over Chakra reached 30!

As soon as he finished the hand seals, a slightly more powerful surge of Chakra flowed from his palm, directly into the already compressed stone. The stone, which had been compressed to the size of an egg, was then compressed again, becoming the size of a pigeon's egg!

"!!" Kamiya Keiyun stared in astonishment at the pigeon's egg-sized, dark brown stone in his hand. He then thought back to the lump of mud he had started with when he left, and its volume had directly shrunk by three-quarters!

"That's it!" Kamiya Keiyun was somewhat excited. What the success of this technique meant was that one cubic meter of soil could be condensed into 0.25 cubic meters of stone!

And Kamiya Keiyun felt that this technique hadn't even reached its limit yet. He had only tried it once or twice. If he pushed further, it might not be impossible to condense it to 0.1 cubic meters, or even 0.05 cubic meters!

For now, it was just Mud to Stone, but in the future, it would be pointing at land and turning it into steel, or touching stones and turning them into gold!

"But why do I feel a sense of closeness to mud?" Kamiya Keiyun felt the mud in his hand. When he had tried to compress the mud earlier, he had felt it. The mud seemed like a part of his own body, exceptionally familiar, and he hadn't even exerted much effort!

However, he hadn't felt this way when he played with water before.

"Is it because I chose to strengthen the muscles in my legs? Or is it because I'm from China, and farming is in my blood?" Kamiya Keiyun pondered, then recalled the electric current on Hatake Sakumo when he attacked, and Shimura Ken's nickname, Wind Ghost. So that's it, this is an affinity! Is it an affinity for a certain element?

So Hatake Sakumo's primary element was Lightning, Shimura Ken's primary element was Wind, then my primary element must be Earth?