"Our main local donor has lodged complaints against a student in this class." The teacher in applied offensive magic let his eyes wander over the class until Ioha's met his. "Care to explain?"
Ioha tilted his head Ai style. "He became violent and I stopped him," he offered.
"Physically or with a force shield?" The teacher was a geek after all. Else he wouldn't have taken up his position out here in the middle of nowhere.
"Non volatile force field," Ioha answered using terminology they had been taught the day before.
"Persistent?"
"Very." Ioha grinned. Anthony had been found when breakfast was served.
"How persistent?"
"I honestly don't know. The field was forcefully dismantled around six hours after being set up." That was academese for how Ioha had left the jerk dangling mid air for an entire night. The class stared at him with joyful glee in their eyes. Anthony Clevasti attended the knightage class as was proper for a noble first born. Knights and spellswords led very different lives, and the mutual antagonism started at school. Anthony being a first class jerk didn't help, and hanging him out to dry for the night made Ioha a hero.
"The Clevastis will file for damages."
There was that. Damages might impact their studies negatively. That made Ioha a villain. "Look," he said. "The involved parties were two outworlders and the Clevasti shithead, I mean honoured eldest son." The outworlder part was the most important here. Isekai represented a source of power unlike anything else known to this world, or at least this geographical region.
A pair of glasses slid down his nose when the teacher nodded. He might be a geek, but he was an experienced geek. Ioha wondered what he had done before he settled down as a teacher here. "Isekai's presence is felt even here," he said and pushed his glasses back up again with one finger. He returned to his blackboard and finished the explanation he had started earlier. Chalk and blackboard. Ioha's grandfather, or maybe even great grandfather, had seen lectures presented that way.
There were other gate hubs as well, but only a few, and the closest a continent away. On top of it all Isekai was the only one connecting Europe with Asia; Gothenburg and Nagoya to be more exact. "If they have a problem with me they're welcome to take it up with the local government in Isekai." Which was the same as Ioha saying: 'don't shit where you eat'.
Their teacher grimaced. While it was clear he sympathised with Ioha there were limits to what he could do. "You do understand there will be repercussions, don't you?"
Ioha did. To his surprise his sabre arrived yesterday. Apparently keeping promises was important here, but the Clevastis would never do any business with him again. Their loss. Ioha represented a new breed of outworlders, one that complemented the more hands on approach of the Japanese. The outskirts of Isekai had exploded with low tech agricultural, architectural and logistic innovations the last two years and the town could handle over five thousand people more now, be they residents, tourists or locals mattered little.
"I understand," Ioha said. "There could be repercussions," he added.
What did matter was that out of that potential five thousand two hundred already lived there employed for a very specific reason. Ioha had seen them himself. Now Isekai had its own formal military. A very small one, but still. Isekai declared itself a sovereign state half a year earlier. Lord Clevasti might not like it, but his troops were likely to be shredded if the tried to change it. Also, for rather obvious reasons the largest of the adventurers guilds resided in Isekai, only possibly outgrown by the one in the capital, which gave the new state a well trained force of over a thousand to call upon should the need ever occur.
The smattering of chalk against blackboard both brought Ioha out of his thoughts and signalled that the teacher had done his duty by informing his student about the problem. "As you see we can divide magic into four main categories. Independent and extended as well as volatile and non volatile. Anyone here caring to give examples?"
A hand went up a few rows above and behind Ioha, near the windows. It belonged to the girl who had tried out her weapons while Ioha waited for his turn. "An arrow made of magic and an aura sword," she suggested.
"Good examples!" The teacher wrote 'arrow' next to independent magic and 'sword' next to extended. "The sword is still in contact with your aura and you can influence it for the entire duration. It is in effect an extension of your aura. The arrow, however," he stabbed the chalk into the blackboard, "can't be modified by the caster after it is released."
"But I've seen independent magic change," the girl protested.
"It can change, yes, but you as a caster can't change it after it's released from your aura."
Ioha nodded and jotted down some notes. He didn't plan to throw fireballs left and right, but knowing he lost control of his spells if he ever allowed them to move outside the range of his aura was important. If that was true. An itch crawled around in his brain they way it usually did whenever something didn't fully make sense. Well, true or not, right now he needed to understand what the teacher said.
"Can I grow my aura?" the girl asked.
Ioha's ears perked up. He hadn't thought of that.
"Yes, but not by much. The width of your own body if you train a lot."
An extra thirty or so centimetres? Not a lot for the fireball kind of mage, sure, but that was a huge difference for anyone manipulating weapons in their hands.
The lecture hall fell silent. Apart from him it didn't seem anyone had grasped the implications.
"So, examples for the other two types?"
Magic geek for certain, but not someone schooled in mathematics. There weren't four main types of magic. There were two axes orthogonal to each other. The pair of independent and extended had nothing to do with volatile and non volatile. One pair concerned space and the other time.
"Healing and, and, well, and leaving Anthony Clevasti hanging in the air," a short ginger boy suggested from the row closest to the blackboard. He had the decency to turn and look at Ioha when he said that.
Their teacher waited for the roaring laughter to stop before he, still grinning, nodded. "Indeed. Healing ends the moment you stop casting it but, as young Ioha here has proven, force fields don't, or at least don't have to."
Another round of mirth filled the hall.
"I want you to remember that you could create a field that requires continuous casting. It's just very inefficient."
Those words proved what Ioha realised just moments earlier. The magic arrow was also an example of non volatile magic just like the magic goo he forced upon Anthony. "Could healing be non volatile as well?" Ioha asked.
"No," the teacher said and shook his head. "Healing is a process. Something changes while you cast. A force field is a state, or at least should be. You could create a process where the field changes its current state to one exactly the same continuously, but as I said, that's inefficient."
Ioha felt a grin spread over his face. So volatile magic was simply an application of a vector of changing states and non volatile the act of creating one state. "So persistent magic is simply a non volatile effect with a long duration?" he tried.
Their teacher scratched his head and looked at Ioha. "I guess you could say that. I'd say persistent magic is permanent under ideal conditions, but it's a grey zone. You can create effects that deteriorates even under perfect conditions."
So persistent was a matter of definition. "You mean I could build a house with magic?"
"If you mean built from magic, no, not unless you accept that it will likely collapse very quickly." A few steps later he had returned to the blackboard wielding a piece of chalk like a weapon. "Remember our dear friend Anthony?"
The class laughed again.
"External intervention will have effects on persistent magic. Depending on magic and type of intervention your persistent magic could wear down slowly, or it could simply collapse when the intervention is strong enough or has gone on for enough time." He accompanied the explanation with symbols and figures that quickly filled the blackboard. "For example the nightlight on the walls of this school will fail catastrophically after heavy rain and needs to be recast, so that's one type of a collapsing effect." The teacher smiled. "Our dear Anthony is an example of the slowly wearing down effect. Apparently they had to dig him out before actively dispelling the remaining effects."
Laughter rippled through the hall again.
"Let me show you the underlying theory." The teacher attacked another section of the blackboard. "As for the house question earlier, assuming that you create it by applying different effects…" He tapped the blackboard with his chalk while he thought. "Like with bricks and mortar but made from magic. The different effects will interact with each other causing interventions just like with other external factors. So your house will either collapse piecewise of deteriorate." The smattering of chalk continued and now the blackboard filled with symbols representing basic but abstract magic theory.
Some of the students groaned, but Ioha loved it. For him there was nothing like a huge chunk of theory for grounding understanding. He vaguely knew he was wired strangely, but who cared? It worked for him. Still, that itch never left. Something about volatile and independent magic bothered him. The lecture continued with more students groaning and Ioha growing happier. There were vague references to poor Anthony explaining different outcomes if Ioha's force field had been a container of water, a magic bonfire and other discomforting ways of suffering.
In the end he couldn't contain himself, and unbid he burst out: "Damn, I never knew Anthony made for such a great research object!"
The lesson ended in a guffaw.