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Kouzuki household, Kazuya had just arrived home and headed for his research center after changing his clothes. He was dropped off by the instructors that went to pick him and Tomoyo up. Kazuya excused himself from going to the dojo today because Jirou was busy dealing with matters that needed to be settled.

*sigh* "Should I just quit the kendo club?" he wondered. Since Jirou and the other instructors have been training with him regularly, he saw little purpose of continuing the activity.

The only purpose his participation in the club had left was the expectations that people had of him. There hasn't been people like Ayame or Tomoyo showing up so there was little point of joining the tournaments with the purpose of finding opponents that could give him a challenge.

Kazuya thought about it as he moved one of the desks. He lowered himself and imbued mana on his fingers before tracing a pattern that slowly revealed a trap door that led to a stairway. This was something that wasn't originally part of the storage building. Kazuya had spent a lot of time making this passageway along with the secret basement that he just entered.

"This room should be strengthened enough" he glanced at the formation on the wall and touched them before nodding to himself. The room had no electricity or wires but the formations provided illumination by using the mana that was concentrated when it detected movement in the basement.

The room was quite spacious and contained one desk that was placed on the side of the stairway leading back to the upper floor. The desk contained various stuff he has experimented with and this was where he kept the book that was given to him by the demon king.

"Now I can finally have a place to practice without worrying about being seen" he smiled.

The room was slowly built by Kazuya to keep the secrets he wanted to hide. It took two years to build this by himself with the body and mana he had but it helped develop both his mana capacity and physical prowess. The room's real purpose was finally going to be taken advantage of today.

"I've been out of practice for so long but I should have already cleared the amount of required mana to start practicing" he closed his eyes and started gathering the memories he needed in his mind.

"Ember" he spoke in the language of the long eared magical race and controlled his mana precisely as he had been taught in his memories. This was not the first time he had tried practicing magic but Kazuya had always been nervous whenever he tried because even he cannot be completely sure that no one would notice especially when he tried to cast eye catching spells. This was the main reason why he thought of building this room beneath his research center.

Magic was never his forte nor did he concentrate on developing his skills with it. He only used healing type magic throughout his journey and with the addition of Gale in his party, he never developed it further to the advanced category.

He never really felt the need to. Though his predecessor was probably one of the most famous mages in Edea's history, the demon race rarely had a magician that could pose a threat to him. Those that did, had been taken down by the teamwork of him and his friends which was the reason why Kazuya was less inclined to develop his magic skills rather than his sword skills.

In this life however, he held a different opinion. Though the demon race did not have much experts in the arcane field, the humans did. Kazuya knew that he had to prepare facing those who were not only clever, but also skillful magicians who knew better than him that they had to avoid a close confrontation with a warrior type like him. Having a concealed weapon would be better than having none.

This was not the only reason he decided to learn and develop his skills and magic more thoroughly. The book that the demon king gave him also held some research on the spells the hero Gabriel had developed in his stay at Edea. Some were even labeled forbidden or kept secret because of the effects it had on people.

"Flame" the ember in Kazuya's hand grew stronger and he could feel the heat emanating from it. That was not all, magic was relatively different from physical type enhancements so the consumption of mana felt very distinct.

He was a warrior type so he immediately noticed the difference. He may have not noticed it because of the enormous mana he held when he was summoned to Edea but now that his mana capacity was leagues lower, the discovery of this made him think about a lot of things.

Kazuya wasn't sure if the people or teachers from Edea noticed this because they were all born with a distinct affinity to mana. He felt that he could improve his control over mana even further if he figured out a unique way of controlling his mana to both his warrior skills and magic.

"I should ask Natsu for advice about this when I find him. For now, I need to focus on learning all I ignored back in the academy he built" he launched the flame on his hand which turned into a fireball that hit the wall before disintegrating.

"Phew…" he tried feeling the consumption. He smiled wryly because he remembered that the games he played always displayed HP and MP bars. There wasn't anything to tell him how much MP he would have left to use magic with so he could only do it by feel.

"Looks like I really have a long way to go" he looked disappointed after casting a few more spells. Though he had grown a lot these past two years, it was not even close to the amount of mana at his disposal back in his previous life. He realized that he had taken a lot of things for granted in the past now that he lost them.

In his current state, he was not capable of practicing magic like he did with his physical enhancement or warrior skills. This was the difference between magicians and warriors; magic involved things like manifesting fire or water so it naturally had a higher cost than simply strengthening one's self.

"Hmm? Why is she here?" Kazuya felt a presence approaching his research area.

"Kazu?" Mei entered the research area. She was already taught the method on how to enter so she could enter it unless an additional lock was cast inside. Kazuya didn't think that Mei would be home before he was done so he didn't bother to cast a lock spell from the inside.

"What are you doing home so early big sis?" Kazuya emerged from the trap door and startled her. She had never seen such a door before and as far as she knew, there were no basements apart from the one in the main house.

"I got a vacation from Kyouko" she told him about what happened earlier and how she got some time off.

"I see…" Kazuya thought for a moment. "I guess I won't have to worry about you overworking yourself too much big sis" a smile appeared on his face. He was actually a bit worried about Mei because of the increasing amount of stuff she had to deal with even with Yui's help.

"I won't have to worry about that much since I have you to help me with fatigue right?" Mei smiled back.

With her discovery of mana, Kazuya had explained to her a lot of things including the positive effects he was responsible for. He explained how he was relieving their fatigue with recovery magic through touch as well as improving both Kyouko and her affinity to mana in the process. He even made a file that made her understand how mana was used.

"Still, you shouldn't rely on mana too much big sis. I've already explained that there is such a thing as mana exhaustion right?" one thing Kazuya didn't explain however, was the difference of mana available on earth compared to Edea. Mei was a resident of earth so she had never experienced or was even aware of such a world and Kazuya intended to keep it that way. Mana was one thing he could explain but the concept of other worlds was a whole other world of concepts altogether.

"I know" Kazuya had always reprimanded her about anything that wasn't good for her so she felt a little embarrassed because she thought that he was like an overprotective lover. "What is that hole on the floor? There isn't supposed to be a basement in this building right?" she decided to change the topic before she dug herself in a deeper hole with her imagination.

"A room I made" Kazuya guided her downstairs where Mei looked around like a curious kitten in a room full of swaying things.

"This… is all powered by mana?" she excitedly touched the walls that illuminated the room. She was baffled at how such a room was made because a lot of effort and equipment would have been needed to make such a sturdy room like this.

"Yes. There is no electricity here. Everything is all thanks to the formations that gather mana in the vicinity" he explained.

"I'm really interested in meeting that person you mentioned that taught you all of this. If we could incorporate this into technology…" Kazuya was quite impressed with her reaction. Mei immediately thought about how it could be applied in their current business which made Kazuya more confident that his big sis was capable of handling the matters of the company without his help and it would still flourish one day.

"I'm still looking for him with the same intentions in mind. The problem is that he rarely checks any means of contact because of his concentration towards his research" this was the excuse he made towards whatever he taught Mei.

Natsu, the person that seemed to have left no traces to let himself be identified was harder to find than Kazuya imagined. He was afraid that his predecessor was one of those recluses who chose to lock themselves up in a mountain after returning to their world. Kazuya didn't stop trying to get in contact with Natsu through the help of the ever-expanding internet but he hasn't had any luck so far.

"That's too bad" Mei sighed in disappointment. "So is this room made to research all the stuff you learned from him in secret?" Mei looked at the spacious room again and imagined all sorts of devices from what she learned.

"No exactly… it is indeed for research but this room is a bit more for practice" Kazuya smiled and took a few steps away from his big sis.

"Practice? You already practice enough in school and that dojo" she assumed that she meant Kazuya's obsession towards getting stronger.

"Practicing this" Flames suddenly burst from both his palms.

Kazuya had been thinking about how to better protect Mei now that questionable organizations have been eying their company. That's why he decided to simply come clean and decided to show her magic. This would be like giving her a weapon that could be used to protect herself in case he wasn't there. The jewelries he developed over the years gave him a sense of comfort but they were still limited to a few uses.

"!" Mei gasped at the sight of the flames that burst from Kazuya's hands.

"This is—" he stopped talking when he saw Mei take off the coat she was wearing and rushed towards him to attempt to put out the fire.

"Huh?" Mei dropped her coat and grabbed his hands and tried to make sure he was fine. She wasn't able to hear anything he said but panicked the moment she saw the flames bursting out of his palm. "Are you okay!?" she blurted out immediately after seeing that his hand didn't have any damage.

"I'm fine big sis. You don't have to worry" he placed a hand on her cheek and stroked it to reassure her. He was startled that Mei panicked like that but he was filled with warmth after seeing her too focused about his well-being.

"That was fire! Are you playing with fireworks or something!?" she calmed down after seeing that there was nothing wrong.

"Umm… that's what I was trying to say. This room is something that I built so I can practice magic spells like that one" a small ember appeared on his palm so that she wouldn't be as startled as she was when he used a stronger flame spell.

"Magic…" Mei tried reaching for Kazuya's hand once more but he retracted it.

"Magic is pretty harmless to the user when it is made from the user's own mana in the casting phase but it will affect anyone else normally so you should be careful big sis" he warned.

"This is unbelievable… this like, like something out of a manga!" her eyes were locked onto the flame. Kazuya could understand how she felt because he had experienced almost the same thing when he first encountered the concept of mana and magic when he was first summoned to Edea.

"Would you like to learn how to use it big sis?" he asked

"C-can I?"

"Of course. I was trying to think of ways on how you can protect yourself if ever you are put in a dangerous situation with all the people that are eying our company. Since mom gave you some free time, some of it can be used to practice magic here"

"What do I need to do?"

"First you need to understand the basics" Kazuya moved to the desk and opened the lock by using his mana. He then took out a notebook which contained the basics of mana he had written for his own research in magic spells and handed it over to Mei.

"This contains everything I know about the basics of magic as well as a few notes that you can choose to ignore if they are not helpful to you. I wrote this to improve my own understanding of magic so please don't hesitate to ask me if you don't understand some things" he showed her the notebook and began explaining the basics she needed to understand before she could cast her first spell.

He wasn't an expert in magic since he was not a mage but he could at least repeat all the lectures he took in the academy by memory. Mei listened attentively and did not hesitate to ask for clarification whenever she didn't understand what Kazuya was talking about. She was already familiar with the concept of mana so it didn't take her too long to understand the basic principles of magic.

"I will be practicing on the other side of the room. For safety reasons, please only try to practice magic in this room. You are not allowed to use any spells outside this room unless I have cleared the spell you are trying to use. I will immediately stop teaching if you play around with magic okay?"

"Do you think your big sis is a little kid?" Mei was a little upset over Kazuya's worries since she was still officially older than him.

"Hehe…" Kazuya let out a dry laugh. He was used to talking like this with all those he taught in his previous life and realized that it had become a habit. He scratched his cheek awkwardly and let Mei concentrate on digesting the amount of information he just shared with her.

"(I don't know if it is the right decision to let big sis learn magic but… I trust her self-restraint and it will surely be a big help in case those scums try and bring her harm)"

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