The next day, Arima woke up on the roof and yawned. He jumped to stand and stretched his limbs.

"My familiars didn't detect anything, huh?"

"…Yes," Night replied with a delay after he almost was thrown away when Arima hopped so suddenly. Now, he was grabbing his shoulder from the wrong side.

"What are you doing?" Arima asked and Night groaned. "Still, I deployed ten thousand of them, how did I find nothing? Or maybe nothing happened this night?"

Night sighed after he was back on Arima's shoulder how he should be. "Maybe. Is that number still the same at least?”

"I checked already. None of them has been destroyed," Arima declared and jumped down from the roof, directly landing in one of the academy's courts. Fortunately, there was no student there. He then directly headed toward his classroom.

"In the end, what do you think they're planning by performing mass murder?" Night inquired when they arrived at the class.

"I don't know," Arima responded and sat down on his seat. "It’s undoubtedly a magic theory that needs the sacrifice of a great number of lives. Well, the first thing that comes to mind is a curse, a large scale one, or maybe something like a plague."

"A curse, huh? Anything else?"

"I don't know, there's not a lot of magics which need a grand scale sacrifice. Well, they could try to summon some evil god or something but I can’t predict what that would produce. One thing is certain though. If it's the preparations to some sort of ritual, then it's definitely not something good for this city," Arima said and yawned. "Ah, damnit, I'm still tired."

Night sat down on the desk. "You look like you don’t care."

"Nah, it's not like that. I mean, I think I'm still human enough to not ignore a mass murder happening right in front of me and the deaths it could cause in the future. But, you're right, it's not even my world, not my duty, and I don't need to help them. But I'm still teaching in this school you know? It would be inconvenient for the city to be attacked or destroyed. Don’t you think so as well?"

Night dryly laughed. "Of course."

An hour or so after that, the first students arrived. When they arrived, they also spotted Arima sleeping on the seat with Night blankly staring at him.

Ultimately, it was Isla who approached Arima discreetly and woke him up. For that, she suffered a cold and annoyed look but it was worth the surprise she gave to Arima. Normally, she shouldn’t have been able to even get near him but at that time, Arima’s mind had been temporarily scattered because of the ten thousand parallel minds he was regulating.

Isla then went to her seat with a very awkward laugh.

Soon after, Ofia and Lena stepped inside the classroom. Both of them had a heavy expression. When she entered, Ofia promptly went toward the teacher's desk. She gazed at Arima who was waiting for her to say something.

But even after a minute, they were both silent and looking at each other.

"Hey, am I supposed to talk first or what?" Arima finally spoke and Ofia trembled.

"Hum, teacher… if I asked you, would you help our city?"

Arima's expression twitched and he poked her with his finger. Ofia looked wide-eyed while rubbing her forehead. "Give me some context, silly kid."

Ofia wryly laughed while her sister also smiled when she looked there. "The results from the investigation about the attackers you saved us from last time. We got them."

"My brother said he felt like they had no emotions when he fought them," she said and Arima nodded. “When we autopsied the bodies, we indeed found out that they were artificial bodies infused with a soul. They had different limbs on their body and even their organs didn't match the others."

"Homunculus?" Arima remarked and Ofia affirmed.

"Yes. From what we know, there aren’t many people capable of doing that kind of work. Much less someone who wants to harm us. In the end, our research spread to the nearest continent, Firnea. We are also aware that its King doesn't want us any good… But the biggest piece of news we got was that two people who were on that continent were summoned and hired by him."

"One was a Z rank mercenary, Arister Zeola," Ofia disclosed and Arima glanced at the actual Arister on the side.

"You don't need to worry about him anymore," Arima said and Ofia slowly nodded.

"I understand. As for the second individual, his name is Ojure Karez."

Arima hummed. "What a weird name."

Ofia bitterly smiled. "Yes, but that person is really a problem. He once visited the Main Land. He is an extremely talented necromancer and healer. He's an expert in everything related to life and death."

"Oh, interesting. So, you're saying that Firnea is planning to defeat you with the help of that man and his expertise, right?"

"Yes," Ofia nodded.

"Then we can also consider that those ‘deviants’ are homunculus too. So, you asked me if I would help you, huh?"

Ofia nodded again, with a very earnest expression. Arima smirked. "Don't worry. As long as I am on this continent, you can expect that I will lend a hand."

Ofia sighed in relief and smiled. "Thank you."

"Sure. Now go take a seat. If you want to protect your city, you'll need to learn how to protect yourself at least," Arima waved his hand and Ofia bowed before going to her seat.

Ten minutes later, everyone was here. Lanya and Karma arrived together, laughing with each other. It was without saying that Arima and Night shivered when they saw this.

The former stood up and sat on his desk. "Well, good morning. Today, I guess you already know what I will talk about. The next one on the list is soul magic," he stated and everyone confirmed with a nod.

"What can I say about the soul…?" Arima muttered to himself. "First of all, you need to know that the two things composing a human are his mind and soul. The two don't have any actual direct connection but can't work properly without the other."

"There’s a question that comes back a lot in my homeland. Where is the soul? There's a lot of different opinions. Most people just say that the soul is connected to our body and doesn't have any real emplacement since it's our life itself. Other say it's distributed among different parts of the body and others say that everything is in the brain."

"To be honest with you, I don't have an idea of what is true and it isn’t really important. The only thing you need to understand is what the soul is and its difference with the mind. The latter represents our thoughts and emotions. Basically, it's what you learn during your life. Your memories and knowledge."

"Soul is a bit different. It's the essence of your life, it's what makes you live. It’s both your life energy and life force. The soul is unique and is usually defined as your personality by your mind."

"Let me give you an example. From your birth to your death, you learn and experience things with your mind. Everything that you saw in your life will be carved in your soul as your personality. Then, imagine you die, and your soul is reincarnated. You reappear in the body of another, with no memories, but the personality engraved on the soul will remain."

"As a result, the newborn who possesses your soul will have the same personality as you had before you died. But the mind will be different from the previous and will have the possibility to alter this blank soul again in the future."

Arima smiled. "Well, this is essentially the relation between the soul and the mind. You should also know that the former is used to identify a person with what you call a soul imprint. It’s said that gods differentiate humans through their soul imprint. There’s also the fact that a person with a bigger soul usually possesses a bigger mana pool and is usually bound to become strong and talented if he lives long enough."

"Before I talk about the practical use, if you remember, I mentioned the fusion of souls in the explanation for the Soul Contract. I said that the soul carried the information of the being in which it resides. So, depending on your race for example, the soul will carry different information and if that info changes, your body will follow accordingly to match it."

"Thus, you have to understand that it's possible to interact with a soul. Which brings me to the practical use of soul magic. You can, of course, create artificial 'essences' to animate familiars and dolls. It's also by the same principle that a soul beast is created."

"But the most valuable thing you can do with soul magic is modifying the soul's 'data'. Imagine, what if you could change the essence of your own life. What could you accomplish?"

The students reacted blankly at first. But then, they remembered the soul contract. The latter allowed the user to fuse with the soul of another living being. It only worked because it was two souls interacting with each other. And it was that exchange that enabled them to transform their bodies.

Then, could they change their souls to their preferences? Could they gain every power they wished for? If they wished for a pair of wings, could they just modify their soul for it?

"Yes," Arima smiled as if he knew what they were thinking. "But," then he said and his students' hopes, that went up to the roof, stopped ascending before it was too late. "It's a really dangerous technique. I assume you understand that if you mess up at 'tuning' your soul, you could end up dead or as a literal monster."

"Of course, I'll teach you this in detail later. But I have to warn you, there's only a small proportion of people who have the precision and talent necessary to do this. And the magnitude and quantity of variations you can give to your soul depend on how resilient it is. So, once again, don't try this alone," he advised and everyone nodded.

They already had learned to never ignore Arima's instructions. "Well, that's it for the soul. Since the beginning, I had nothing much to say. It's a subject very theoretical and abstract.”

"Well, since we have still a bit of time, let's talk about neutral magic. Don't worry, it will be even briefer than soul magic. Neutral magic is basically mana in its original and primal form, without any attribute or theory behind it whatsoever."

"You use neutral magic to strengthen your body or to create basic physical shields or weapons. It's also used for what we call psychokinesis. This," Arima pointed at a book and made it float.

"When you use neutral magic, you can think about it as a physical attack or an interaction. Normally, you all should’ve already mastered it. Every mage needs to know how to use it and it’s very important to train. Because the more proficient you become with neutral magic, the better your control over mana becomes. It’s a crucial skill for any magician and never should be put aside."

"Next time, I'll talk about death, life and time magic. The kind of hard ones, especially time,” Arima smiled and clapped. "Time to change class."

For the rest of the day, Arima sustained his lessons and answered the questions of his students. In a general lecture, he could only give the basic stuff in the simplest way possible so when his students would personally come to him to ask something, he would always give more details.

The next night, Arima's familiars detected a movement. "Finally," he yawned while resting on the PA's roof.