"Huh?", Yao Lian looked towards Esme. She noticed how her narrowed eyes and that smirk appeared as if she was trying to push a scam deal on her, trying to lure her into something shady, prompting her to turn towards Ryuk as she noticed him offering her a book just based on a promise.

Seeing both of them, Yao Lian thought that something was definitely wrong, causing her to take a step back as she observed both of them, feeling that it could be possible that it was a trap to lure her in. This caused her to look towards Ryuk with a trembling gaze as she lowered her head and added, "Young Master Rui ke, I would like to make some other deal instead of a promise."

She found the promise aspect completely suspicious, given that there wouldn't be any guarantee to reassure them of her loyalty, making her doubt that it was some scheme to lure her.

"Hm, then tell me where Liu Wei is," Ryuk said, seeing how at least this woman was smart enough not to take the promise. Even though it was inevitable for her to get enslaved, he still gave her a believable proposal in exchange for the book.

After all, he knew well about people's personalities; he recognized that by giving such a simple task, she would definitely accept his previous offer.

In the end, it is human nature to regret their initial decisions while being unaware that maybe their present ones could be better than previous ones—a cycle that never ends.

'It was easy', Yao Lian lifted her gaze towards Ryuk, feeling that it was really easy that she requested to change it and he just changed it, making her think that maybe the promised thing was not something to lure her. Prompting her to add, "I can take you to him, but regarding the previous offer, I would like to accept it."

Yao Lian weighed the pros and cons and understood that right now this man was at least as strong as Wei family's head to have a seat beside him, making her clearly think that this could be her only chance to make herself likable in his eyes. Once she mastered the techniques from that book, she could easily deal with him in the future.

After all, it was just a mere promise of eternal loyalty without any base to support or force her into it.

"Then recite it," Ryuk said, seeing how obvious she had fallen for the trap and accepted to promise him her loyalty. He told her again, so that once she got enslaved, she wouldn't blame him for unethically forcing her into slavery.

"I, Yao Lian, promise to serve Young Master Rui ke with eternal loyalty," Yao Lian said, closing her eyes as she lifted one hand with a hollow tone, casually taking the oath, knowing that he couldn't force her into just following what he wanted, making her take it as just a momentary assurance to get her hands on that book.

"Khucek?! Haah! Haah! Argh!" Liu Wei clenched his chest as he felt intense pain assaulting his body. It was as if the internal energy he had thought to gather from the surroundings was rampaging within his veins. He coughed up a mouthful of blood.

"M-master, I can't," Liu Wei said, his face contorted as he clenched his chest, falling on the floor and coiling his body as he once again told his master that the method of detoxifying his body using the outer internal energy was impossible.

Naturally, once the energy core first synthesizes the outside energy, it must adjust it to the wavelength and compatibility with the body and then store it into the dantian or any energy sources available in a person's body. This holds true for all forms of energy, making it impossible for someone to directly take energy from outside and use it by using their body as a medium.

// Avoid being foolish; while it might seem unachievable, once you accomplish it, you'll harness the energy of the whole world, comparable to an endless source of power. //

A voice reverberated inside his mind, reminding this boy who was destined to reach new heights how crucial it was for him to learn this method.

Normally, it may appear that all beings use energy or its different forms available in the atmosphere, just like mana, which is abundant. But in truth, all kinds of energies are first synthesized inside one's body by their mana heart, energy core, or whatever method they have developed to remove the impurities and violent nature of the outside mana and store only its pure form.

This is also why someone's energy vessel depletes after a long battle, since they are technically not using outside mana, but their own bodies, which is nothing more than a form that gets synthesized from outside; like one having an ocean full of water but they could only drink that which is free from salt and impurities stored in it.

This is the same case for energy too; one needs a clear and clean form of it to use. By learning the technique he was trying to teach this boy, who had the potential to reach that peak, it was possible to directly use the ocean water.

Of course, it was impossible, considering that once you become a medium between outside mana and the output of your energy, the outside mana will overwhelm and dissolve your body in it, clearly causing your presence to disappear.

However, for the voice, it was the only chance to link and gain complete access to infinite mana.

With it, the owner of the voice would be able to reconstruct its body, even though in the end, Liu Wei dies.