January 7, Sea Circle Calendar 1504.
After the ordeal with the tsunami, Ray, Vic, and Anthony continued on their way to the Oykot Kingdom.
Noah, meanwhile, had Lilith take Lilian to the waters where the volcano had erupted.
There was, naturally, a reason he sent the two girls to the site of the eruption.
At the spot where the undersea volcano had erupted, a stretch of land several kilometers in radius had appeared. It had clearly been formed by the eruption.
Besides the solidified obsidian and volcanic rock, there was still plenty of magma at the center that had yet to cool and harden. The molten magma flowed out from the vent in every direction, with clouds of scorching white steam rising from it now and then.
A flame descended from the sky, then turned into a girl wearing a Gothic dress. It was Lilian.
Gently flapping her wings, Lilith watched her younger sister standing at the edge of the crater, a look of concern on her face.
Although Lilian had left her Elementalization state, that did not mean the magma flowing in the crater could threaten her.
After all, Noah had taught her a great deal of scientific knowledge, as well as various ways to develop a Devil Fruit. Her Flame-Flame Fruit had already surpassed those of its previous users.
Why had the Flame-Flame Fruit performed so poorly in Ace's hands?
The answer lay with Ace.
Expecting an illiterate person to develop the Flame-Flame Fruit to its full potential was no different from expecting to get rich by buying lottery tickets.
Garp had left Ace with the mountain bandit Dadan to raise, and Ace had learned to read only because the bar owner in Foosha Village taught him. In such an environment, his ability to read and his grasp of some everyday knowledge were essentially the result of her diligence and care.
Noah was no scientist, but as a science graduate who had lived through the age of the information explosion, he did have some understanding of scientific knowledge.
The direction in which the Flame-Flame Fruit should be developed lay not in the flames, but in the word "burn."
To burn meant combustion.
Combustion was the process by which matter entered a plasma state.
At its core, the Flame-Flame Fruit simulated the combustion of matter. Ordinary fuel burned in air at a temperature of six to seven hundred degrees Celsius, which was also why Ace could not raise the temperature of his Flame-Flame Fruit.
How, then, could the combustion temperature be raised?
The answer was naturally to choose a more suitable fuel and oxidizer.
The substances Lilian was simulating for combustion were pure oxygen and hydrogen. Their combination raised the combustion temperature to 2,830 degrees Celsius.
The magma before her was only a little over a thousand degrees Celsius. Not only was it unable to hurt Lilian, but it would instead be burned by her flames.
Of course, Lilian was not here to show off how her flames were hot enough to burn magma. She was here to enter it.
Lilian returned to her Elementalization state and plunged headfirst into the magma lake inside the crater.
Once in the magma, she felt no discomfort. Instead, her body felt pleasantly warm, as if she had returned home.
Lilian did not linger near the surface of the magma lake. After estimating how much stamina she had, she quickly drilled deeper underground.
As she descended, she felt the temperature of the surrounding magma slowly rise.
Only when she reached a stratum at 2,830 degrees Celsius did Lilian feel a scorching heat. Then she began using her special Observation Haki.
That was right. Lilian had her own unique Observation Haki too.
Originally, her talent for Observation Haki had been as ordinary as Lilith's.
But after eating the Flame-Flame Fruit, she followed Noah's suggestion and combined her fruit ability with Observation Haki, developing a form of Observation Haki unique to her: Thermal Sensing Observation Haki.
She could see the temperature of all matter, and her Observation Haki could also detect changes in the temperature around her.
She was using it now to carefully sense the heat deep within the magma and the source of that heat.
Before long, Lilian noticed some special substances in the surrounding magma. They continuously released heat, steadily warming the magma and water vapor around them.
Is this the radioactive material Noah mentioned? The energy produced by elemental decay actually releases such a vast amount of energy.
Lilian tried to simulate the process of elemental decay so her fruit ability could undergo a further transformation.
Unfortunately, even after expending most of her stamina, she still failed to simulate the slightest sign of elemental decay. Unable to achieve what she wanted, Lilian could only hurry back to the surface.
Lilian burst out of the crater again and saw her older sister, who had been waiting for a long time.
"Lilian, are you all right?"
Lilian shook her head. "I'm fine. In my Elementalization state, radioactive material can't hurt me. I just didn't manage to simulate elemental decay this time."
"Don't do anything reckless. Noah warned you that your body isn't nearly strong enough to support Elemental Decay Mode yet."
Lilian had firsthand experience of that. While trying to simulate it deep in the magma, she had felt as though she had run into a high wall.
Of course, Noah had warned her about this long ago, telling Lilian not to get her hopes up.
The main reason he had not objected to Lilian going deep into the magma was that he wanted her to become familiar with it in advance, as well as with the radioactive material hidden in its essence.
Clearly, Sakazuki had not developed the Magma-Magma Fruit to full Awakening. If he had, he would have been able to use radioactive attacks, and his maximum temperature would have exceeded three thousand degrees Celsius.
The upper limit of the Flame-Flame Fruit, meanwhile, was Sun Mode.
This was the development path Noah had mapped out for Lilian.
First stage: the limit of compound combustion (4,990 degrees Celsius).
Second stage: elemental decay (first-stage Awakening).
Third stage: elemental fission (second-stage Awakening).
Fourth stage: elemental fusion (full Awakening).
If Lilian could reach full Awakening, she would become a new sun.
For the present Lilian, however, that prospect was still a little too distant.
She had not even reached the temperature limit for compound combustion yet, much less entered Elemental Decay Mode.
Lilian did not give up right away. She stayed at the crater for another half a month or more, diving deep into the magma every day during that time to carefully sense the process of elemental decay within it.
Although she failed to simulate Elemental Decay Mode, she still gained considerable insight and made a number of discoveries.
For example, she came up with a preliminary concept for Flame God Mode, a special mode created by using simulated solid fuel as a skeleton and simulated liquid fuel as muscles.
After entering Flame God Mode, Lilian could turn into an enormous Flame God giant or form a Flame God exoskeleton. In this mode, she could even swim and walk in the sea.
For another, by observing water vapor deep underground, she conceived the techniques of the Steam Dragon Series.
Unlike straightforward flame attacks, the Steam Dragon Series used high-pressure, high-temperature steam to kill and injure enemies.
Feeling that it would be difficult to gain any further insight from the magma, Lilian decided to return to the Rum Kingdom.
As Lilian and Lilith returned to the Rum Kingdom, Ray, Vic, and Anthony finally arrived in the Oykot Kingdom.