[Note up front: The plot may move slowly, and some people may think the protagonist has changed, but he hasn't. Rus is still the main character, with the kingdom's development as a secondary focus. The protagonist won't disappear from the story until the war arc.]
"Every unoccupied room in Herundis Manor was enchanted with the Dragon Clan Rune Secret Technique, expanding its interior space. So from the outside, this is just a room, but inside, it could be as big as a central plaza."
Toriya pointed to the shelves, where each compartment holding scrolls was protected by a translucent barrier.
"These translucent barriers are a safeguard. They provide a second line of defense in case a thief breaks through the first, and they also keep spells within one scroll from affecting the others when cast."
As Toriya spoke, she whistled.
A mechanical flying craft, built with intricate mechanisms, came to a stop in front of the three of them.
"Father said that this collection of scrolls can convert combustible energy sources such as coal, fire crystals, and combustible ice into the energy of heaven and earth. The cost isn't proportional to the output, but the potential is enormous."
Toriya paused, then continued to Yang Xuanmin and Luo Yinyao.
"Once we reverse the cost ratio, Soul Tools will no longer depend on Soul Masters to fill Soul Power storage containers—Milk Bottles—with Soul Power."
"So your father saw its potential, too, and put it in the most valuable golden section, hoping someone might expand on this line of research. We'll use the flying craft to move between sections so we can save time and deliver this to Venicia."
After thinking it over, Yang Xuanmin asked Toriya, "Do you mean Soul Tools could be powered by machines instead of Soul Masters?"
"That's