The 'things' active in the underground world weren't limited to the Bone Race, as there were also various dangerous creatures.
Those within the 'normal' size range usually moved in groups, appearing in large numbers, while those beyond the normal size typically acted alone.
This pattern wasn't absolute, but so far, almost all the creatures they encountered followed it.
After traveling through the underground world for over a month, besides the Bone Nightmare and Bone Minotaur they had encountered earlier, they also came across many branches of the Bone Race, most of which still had some muscle texture and even eye features.
Compared to the Bone Nightmare and Bone Minotaur, the Bone Race creatures they encountered later didn't pose much trouble.
Ultimately, it was because they lacked the 'reversion' ability of the Bone Nightmare and Bone Minotaur.
Afterward, Law pondered the restorative ability of the Bone Nightmare and Bone Minotaur. He thought that even drinking hundreds of barrels of milk for calcium wouldn't allow for such rapid recovery.
Another point was that the severed bones automatically sucked back into place.
The scenes of recovery gave the impression of a film playing in reverse.
The effect of Dark Sonata's piano solo was to strip the performer and listeners of flesh and blood, turning them into skeletons. It was unclear if it hid a 'reversion'-like ability.
Unfortunately, the cost of performance was too high, leaving no opportunity to verify the guess one by one.
For now, Law didn't dare use the piano solo lightly, nor did he know what secrets the complete forms of the Bone Race held.
'If one could master 'reversion' in the flesh, perhaps it meant immortality?'
Over the month, besides this occasionally recurring speculation, another discovery left Law somewhat regretful.
After breaking through 80%, traveling through the underground world became much easier. He could handle various creatures attacking from the darkness with ease.
Among these creatures, there were plenty of B-grade ingredients, and they often encountered A-grade ingredients as well.
Law felt that as long as he stayed in the Dark Continent for a while longer, it would be easy to break through 100% of his stats.
However, after eating A-grade ingredients, his stats did not increase at all.
Before his breakthrough, A-grade ingredients had at least provided some growth.
Now, after breaking through, there was no reaction whatsoever.
This discovery meant losing one way of improvement.
Initially, it was quite regrettable. After all, having one more way to improve meant having an additional path.
Then one day, Law encountered a turtle-like creature that knew how to use Nen. It was an A-grade ingredient. After some effort to deal with it, he consumed it, and his stats increased a tiny bit. Though still low, it was growth, which is good news.
This indicated that after breaking through 80%, only A-grade ingredients that could use and retain Nen would increase his stats.
While A-grade ingredients were relatively common on the Dark Continent, those that could use Nen weren't as easy to find.
Besides providing stats, the turtle's meat had another effect, which is temporarily increasing his Aura, similar to a blue potion.
Kuro's space didn't have preservation effect. Meat stored there would eventually rot, but Law still placed the remaining turtle meat inside.
They continued exploring. It had been one month and twenty days since leaving the Slu Tribe's dwelling.
Law's group had somewhat adapted to the dark environment, but they began to feel stifling heat, with even the faint breeze disappearing.
One day, they finally saw light in the underground world.
It was red light, like the glow from red-hot iron, emerging from the rock walls or stones ahead. Waves of oppressive heat occasionally washed over them.
"This is the entrance to the earth's core area." Law said, looking at the scorching rock path.
The Slu Tribe had once lived here, using the natural terrain to defend against external threats, allowing the tribe to grow safely.
Previously, hearing Slubin's tales about the earth's core area had seemed unbelievable. Now, seeing it with his own eyes, he could only marvel at the Dark Continent's various unreasonable aspects.
The rock walls, the stones… all were glowing red from sustained high temperatures, yet their forms showed no distortion, like endlessly burning embers.
After standing near the entrance to the earth's core area for just a while, Tonpa was already drenched in sweat. He felt that if he held a skewer of meat a little closer, it might cook on the spot.
If they were to enter the earth's core area, they couldn't step on the red-hot rock ground.
Biscuit pointed at the scorching rock path and said, "The Chief mentioned this place, but the temperature and area didn't seem as extreme as they are now."
"Yeah, probably changes after years of evolution." Law nodded.
Slubin had mentioned the entrance to the earth's core area. Long ago, the rocks were under sustained high temperatures, but among the many high-temperature zones, there were small low-temperature patches.
Unlike now, where everything was red-hot like branding irons, casting such vivid red light.
To put it simply, the entrance to the earth's core area used to be like incompletely burned charcoal, but now it was like charcoal burning at full blast.
"We can't go in, right?" Tonpa glanced at the scorching entrance, then looked back at the darkness far behind them.
Hearing this, Law and Biscuit remained silent, simply staring quietly at the scorching entrance.
Inside, Calamities and Hopes coexisted. Besides the Chasefire Stone, there were other products as well.
Leaving aside others, the Chasefire Stone alone was an extremely abundant energy source, thermal energy, with many uses in the human world.
"I want to go in and take a look." Law suddenly said.
He wanted to enter not to obtain the Chasefire Stone but to see with his own eyes the earth's core area that Slubin had briefly described.
"How do you get in?" Biscuit asked.
Law thought for a moment and said seriously, "By not stepping on it."
Upon hearing this, Biscuit massaged her forehead and said, "That's true, but but what if there's an accident?"
She knew how Law planned to enter the earth's core area. It's nothing more than using Emission-Type techniques to control his body, suspended in the air, and moving slowly and steadily past the high-temperature, scorching rocks on all sides.
Although Law had a technique called [Sky Walk], judging from the entrance to the earth's core area, the interior likely had complex, winding terrain.
Using Sky Walk might lead him to bump into narrow passages.
"So I plan to go alone." Law said with a smile.
Biscuit said calmly, "I don't agree."
"Uh…"
Law was momentarily speechless. He didn't want to defy Biscuit, but he really wanted to go in and see.
After thinking for a moment, he shook his hand and summoned Kuro, "Don't worry about me. I still have Kuro to use as a stepping stone."
Kuro had just appeared when he heard Law's words. Veins bulged around his eyes as he glared angrily at Law.
Law's determination to enter was firm. Biscuit could see this and knew that even eighteen oxen couldn't pull Law back now.
Helpless, she could only agree.
The obvious changes at the entrance to the earth's core area excluded Tonpa and Biscuit. Only Law could attempt to enter.
Unfortunately, while Law's ability could extinguish Feitan's Rising Sun, it couldn't eliminate the thermal energy here. The scorching rock ground drew endless energy from the earth's core, which is beyond human power to resist.
In the end, only Law entered the earth's core area entrance by floating.
He had water algae attached to his body. After infusing it with Aura, it continuously produced clean water, but the high temperatures quickly turned it into steam. Law controlled this steam, directing it into his body to maintain hydration.
Thanks to breaking through 80%, his control had improved, allowing him to perform dual-focused Nen Control.
Suddenly, Law spotted a small plant ahead, standing upright on the rocky ground. It was rooted in the high-temperature rock yet had a vibrant green appearance, radiating vitality and utterly ignoring the surrounding heat.