Upon reaching the early stages of the Yellow Extreme Realm, the "Qi Pool" expanded several times, growing to the size of a basketball.

The true energy in the Qi Pool remained scarce, only forming a mass the size of an egg, less than one-tenth of the Qi Pool's capacity.

Only by filling the Qi Pool with true energy could one advance to the next realm, the mid-stage of the Yellow Extreme Realm.

Zhang Ruyi sat cross-legged, closed his eyes, and activated the Martial Seal on his brow, initiating the cultivation of the first layer of the "Imperial Scripture of Nine Heavens," known as "Supreme Yellow Realm of Heaven."

True energy flowed out from the Qi Pool, circulating throughout his body along the opened meridians. With the circulation of true energy within, Zhang Ruyi's body seemed to transform into a vortex, slowly absorbing the spiritual energy between heaven and earth.

The spiritual energy of heaven and earth flowed into the Martial Seal on his brow, which then transformed it into true energy, storing it in the Qi Pool. The true energy flowed out from the Qi Pool, circulated through the meridians, and traversed the entire body.

After completing nine cycles of true energy circulation, Zhang Ruyi opened his eyes once more, finding that the amount of true energy within his body had doubled, reaching one-tenth of the Qi Pool's capacity.

Although another warrior would have been ecstatic to increase their true energy within such a short period, Zhang Ruyi was dissatisfied. "To cultivate for nine cycles and only increase my true energy by such a small margin, it is too slow! If only I could obtain a spiritual crystal, then my cultivation speed could double!"

It should be noted that Zhang Ruyi was cultivating the "Imperial Scripture of Nine Heavens," and the speed at which he absorbed true energy was originally faster than those practicing inferior martial arts. His current cultivation speed naturally left him feeling unsatisfied.

If he could obtain a spiritual crystal, it would significantly enhance his cultivation speed. A spiritual crystal was formed by the gathering of spiritual energy, and it could be obtained from natural crystal veins in the earth or extracted from the bodies of savage beasts.

The value of a single spiritual crystal generally equaled that of a thousand silver coins, a sum that was beyond the reach of Zhang Ruyi and Lin Fei, making it unaffordable.

Upon realizing this, Zhang Ruyi's heart stirred, and he immediately took out the white crystal-shaped stone that he had been carrying. Could this be a spiritual crystal?

As true energy circulated within his body, the Martial Seal on his brow immediately manifested as a coin-sized circular halo. A white true energy shot out from his brow, striking the white crystal.

A set of four ancient characters suddenly appeared on the surface of the white crystal.

This was extremely strange! Zhang Ruyi had never seen such characters before, yet he immediately recognized them—"Space-Time Crystal."

In the previous life, Zhang Ruyi had infused true energy into the white crystal, but had never caused these characters to appear on its surface.

"In my previous life, my cultivation was hundreds of times stronger than it is now, yet I never caused these characters to appear. This time, with only the initial stage of the Yellow Extreme Realm, the white crystal exhibited a change. It indicates that the reason is not the intensity of true energy, but rather the attribute of true energy."

For instance, a warrior with the Flame Martial Seal would achieve the best results with a fire-attribute spiritual crystal, enhancing their cultivation speed threefold. Using an ordinary spiritual crystal would only double their cultivation speed.

In the natural world, ninety percent of spiritual crystals had no attributes, much like ninety percent of warriors who could only manifest Martial Seals without attributes.

"Could it be that the Martial Seal I activated possesses a certain attribute that coincides perfectly with this Space-Time Crystal? Wait, what exactly is a Space-Time Crystal?"

In his previous life as the son of the Emperor of Light, Zhang Ruyi had heard of many attribute-based spiritual crystals, such as the Scarlet Flame Crystal, Mysterious Ice Crystal, Thunderbolt Crystal, and Dark Blood Crystal, but had never heard of a Space-Time Crystal with a space-time attribute.

That was because time and space were entirely beyond human control, and even gods could not manipulate time and space, as they were subject to the rules of time and space.

Support the creativity of authors by visiting Royal Road for this novel and more.

Just as Zhang Ruyi was still deeply perplexed, a halo appeared on the surface of the Space-Time Crystal, forming a vortex that enveloped his body.

Feeling a sudden whirlwind, Zhang Ruyi found himself in a sealed space, landing heavily on the hard ground.

Fortunately, having completed the Marrow Cleansing and Arterial Refinement, reaching the early stage of the Yellow Extreme Realm had significantly strengthened his body. In the past, a fall like this might have been fatal to his frail body.

As he got up from the ground, he stretched his sore muscles and began to observe the surroundings of the enclosed space.

This space was entirely sealed, without any doors or windows. It was roughly ten meters in height, with a length and width of about ten meters as well.

"How did I get in here? Where am I? Huh! There's a stone platform over there!"

The entire space contained only one stone platform, upon which lay a rolled-up painting and a silver iron book. Apart from these, there was nothing else!

Zhang Ruyi attempted to pick up the painting, but it was incredibly heavy, seemingly fused with the stone platform. No matter how much force he exerted, the painting remained immovable.

Since he couldn't lift or unroll the painting, Zhang Ruyi temporarily gave up and shifted his focus to the thin silver iron book.

The surface of the silver iron book bore four words: "Secrets of Space-Time!"

This time, Zhang Ruyi was prepared. He circulated true energy throughout his body, mobilizing all his strength to open the first page of the "Secrets of Space-Time."

"Is it really this... easy?"

Flipping through the "Secrets of Space-Time" was effortless, requiring almost no effort at all.

Shaking his head in disappointment, Zhang Ruyi stopped circulating true energy and carefully read the "Secrets of Space-Time."

The first page of the "Secrets of Space-Time" did not contain any cultivation secrets, but rather the notes of the former owner of the Space-Time Crystal, a sage named "Sage Mustard."

After reading Sage Mustard's notes, Zhang Ruyi finally understood everything.

"So, the Martial Seal I activated is actually the Space-Time Martial Seal. According to Sage Mustard, not one in a hundred million people can activate the Space-Time Martial Seal. Throughout history, there have been only two individuals, including myself, who have been able to do so."

"Sage Mustard was the second person to activate the Space-Time Martial Seal, but according to the records in the 'Secrets of Space-Time,' he died over ten thousand years ago. Ten thousand years ago was already the Middle Antiquity era, a time far removed from the present."

The space Zhang Ruyi currently resided in was the inner space of the Space-Time Crystal. Time flowed differently within this inner space, where three days passed inside for every day that passed outside.

Zhang Ruyi was overjoyed, exclaiming, "Three days of training inside equates to only one day outside. This means I have three times the training time compared to others! This is truly wonderful."

Zhang Ruyi tried to turn to the second page of the "Secrets of Space-Time," but no matter what method he used, he couldn't open it.

"It won't open again."

Zhang Ruyi felt an urge to throw the "Secrets of Space-Time" to the ground, but suddenly, he noticed a small line of text at the bottom of the last page of the first chapter.

"When reaching the Small Extreme Position of the Yellow Extreme Realm, infuse true energy into the painting to open it."

Zhang Ruyi once again focused his attention on the painting, speculating that it must contain some mysterious technique related to time and space.

"Strive to cultivate and break through to the Small Extreme Position as soon as possible. I wonder what secrets lie hidden within the painting?"

The "Small Extreme Position" was the fourth minor realm of the Yellow Extreme Realm, followed by the Medium Extreme Position, Large Extreme Position, and Great Perfection.

Feeling a pang of hunger, Zhang Ruyi immediately emerged from the inner space of the Space-Time Crystal and returned to his room. With the Space-Time Crystal in hand, he now had a greater chance of reaching the late stage of the Yellow Extreme Realm within three months.

Zhang Ruyi, Lin Fei, and the maid Yun'er sat down to have breakfast together.

They ate only white rice and steamed buns, without a trace of meat.

For warriors, their physical exertion was much greater than that of ordinary people, making their food intake particularly important.

The princes and princesses who had activated their Martial Seals no longer ate regular food and consumed "Blood Pills" refined from the blood of savage beasts. One pill could replenish their energy for an entire day, even after a day of practicing martial arts, without feeling hungry.

Furthermore, taking the Blood Pills could enhance their vitality, strengthen their physique, and increase their physical strength.

Even if Zhang Ruyi ate eight meals a day, rice and steamed buns alone wouldn't suffice to meet his body's demands.

"Son, now that you've activated your Martial Seal, you can no longer eat regular food. Take these ten Blood Pills for now. If they're not enough, I'll figure something else out," Lin Fei said, taking out a jade bottle and handing it to Zhang Ruyi.

Zhang Ruyi, in the midst of nibbling on a steamed bun, was surprised that Lin Fei could afford ten Blood Pills. "Mother, each Blood Pill costs five silver coins, so ten Blood Pills amount to fifty silver coins. Where did you get so much money?"

Lin Fei smiled and said, "I always find a way."

Yun'er, standing behind Lin Fei, added, "Madam sold her favorite Golden Hairpin and exchanged it for the ten Blood Pills!"

Lin Fei lightly scolded Yun'er with her eyes, as if reproaching her for being too talkative. Then she continued, "Son, don't think too much about it. As long as you can become a true warrior, I will support your cultivation even if I have to sell all my jewelry."

Zhang Ruyi was deeply moved, tightly gripping the jade bottle in his hand, biting his lip. He wanted to tell Lin Fei that he had already become a true warrior, but he couldn't. It was too fast to establish an air pool in just one night, and if the news leaked, it would surely reach the ears of other princes and queens. By then, it would harm both him and Lin Fei.

Right now, he was still too weak and needed more power.