Rewrite

Ryuu: " if they used the Grand Master, they will be able to make a human as a source of life."

Yuuya: " explain more please, it's not like that we all know this Grand something?"

Ryuu : " first, let me explain more about the Human life source. As my grandfather was a magician, he believed that to get the power, we should give life. But if we want to make human's life a source of energy, we should give that life slowly so that we receive the energy. But grandfather said that we don't know how to take life slowly, we only know how to kill, that means taking life all at once, that's why the energy can't last for more than a few seconds. So he assumed it can't be possible. But I've discovered another way..."

He said and searched through some old documents.

Ryuu: " the Grand Master was once a sort of magical circuit that can convert any action, even breathing, to energy. But as far as I remember, it was abandoned because there was no one able to complete it. To think Innovators has someone to complete working on it..."

Yuuya : " so how can this Grand Master make the Human life source possible?"

Ryuu: " by converting the ability to live itself to energy."

Jin: " what do you mean?"

Ryuu: " we don't need to take life to produce energy, we have to let the human we use as a life source live. If he lives, the Grand Master will convert his life to energy. The more he lives the more energy we get. It may need a complicated magical calculations but it is still possible."

Jin: " why do they need the Human life source so bad?"

Ryuu: " the Golem was summoned by the god of darkness from the hell. To bring it here, the god of darkness had to give it a life."

Yuuya: " a life?"

Ryuu: " the creatures from the hell are considered for us as dead. They can't be brought here if they can't live, so the god gave it a life to be able to stay here. The Human life source is somehow doing the same thing. By transferring the power of life to that Golem, they will be able to summon it."

Yuuya frowned a little.

Yuuya : " can we trust all this?"

Ryuu: " you're free to trust it or not, but I told you about what I had been observing and studying for nearly half of my life until now."

Ryuu turned to Jin and said.

Ryuu: " if you don't mind, I want to keep those documents with me, maybe I can find something useful."

Jin sighed, maybe confused because of all the things he heard and nodded at him.
Ryuu stood up and said.

Ryuu: " ok then, we better go back up to the library."

They returned back and Yuuya and Jin were about to leave when Ryuu stopped them.

Ryuu: " listen, as long as Ban is fine, you can come back here and ask for whatever you want, but if something happened to him..."

Ryuu gave him a pointed look and Jin nodded.

Jin: " I will remember this..."