"Well then, nice to meet you, everyone! I'll be your main instructor for Magic, Sitri Serafall~! You may call me Sera-chan~!" Serafall introduced herself to the Shinigamis obediently sitting on chairs with desks in front of them in an open field that reeked of destruction as it's the same field that they used to test their abilities.
The silver-haired man raised his hand and Serafall immediately pointed at him, "Yes, Gin-chan!"
Gin almost fell off his chair when he heard how she called him, "...Err... It looks like you already knew all of us?"
Serafall placed both of her hands on her hips and proudly declared, "I wouldn't let these girls meet you if I didn't know anything about you guys."
"And they are?" Gin continued asking.
"They're your instructors too."
Just a step behind Serafall, the trio silently stood beside her while also curiously measuring the Shinigami.
Everyone was shocked and looked at the girls who didn't look any older than 20 years old, "Them?"
"They're young and innocent, yes. But don't let their looks fool you. Aside from experience, they are not inferior to any of you... Well, except for that old man. That old man is an outlier."
Showered by skeptical looks, the trio didn't back down. While they didn't reveal their capabilities to anyone until Kisuke discovered them and they don't know the full extent of what they can do, they're still confident and proud of their achievements. In a world where might is right, cowering would only allow for anyone to take advantage of you. That's how Sona and the others taught them in the Ouroboros Academy.
"She's right. You can't underestimate them." From a distance, Kisuke arrived with Tiamat behind him. As they approached them, he continued, "Even I have to be careful when they stack up."
"Wait... Even in the form you showed us last time?" Furoufushi hurriedly asked.
However, Kisuke just repeated his words, "As I've said, I have to be careful."
"Ho ho... What about her?" Yamamoto, whose sight went back to Serafall, asked with interest, "What about her?"
Kisuke stopped walking and so did Tiamat. He first looked at Serafall with a small smile plastered on her face then back to Yamamoto. Remembering their 'spar' back in the Dungeon World, Kisuke shivered a bit, "Aside from you, the others would be lucky if they could survive once she gets serious. And even if you can resist her attacks, it'll be hard for you to deal substantial damage to her."
An even greater surprise shook everyone. After all, who is Yamamoto Genryūsai? He isn't just the founder of the Gotei 13, but also someone who's capable of destroying the Soul Society just by releasing his full power. The man in question, however, just smiled softly, "That's interesting. I'm looking forward to the future."
'How strange. Has this old man always been this competitive?' Kisuke, of course, didn't explain it any further because they won't be able to wrap their heads around the concept of Super Devil, and Serafall herself becomes immortal as long as she has enough fuel to keep her transformation going.
"We won't just be teaching you how to detect and utilize Magic, but also how to utilize another form of power now that you have physical bodies." Serafall continued and forcefully changed the subject, "This is especially useful for someone who's having a hard time using Magic."
Retsu and Batsu'unsai's ears immediately perked up. Out of everyone, they're the only ones who seemed to be having a hard time using this strange new power. They have no problems detecting it, but somehow, they can't properly manipulate even the simplest spells.
"Also, you might have noticed that your Reiatsu doesn't strengthen your body as much as it would previously and that's only natural." Serafall explained while taking out a wide whiteboard and a marker to write down on it, "Your Spiritual Power came from your souls and while you can use it over a physical body, it's mostly suited for a spiritual one due to the nature of its existence.
"However, that doesn't mean that the physical body doesn't also have something suitable for it. If Spiritual Power comes from the deepest part of an individual, the one suitable for physical bodies comes from the world itself, more specifically, the life present on it.", Serafall finished writing on the board and faced everyone again, "It has many names like Chakra, Qi, Life Force or Breathe of Life, however, we mostly call it Ki. Like Magic Power and Spiritual Power, Ki is another form of energy that is generated just by being physically alive."
'Since Ki is a testament to the existence of life itself, I'm actually surprised that no one uses it here. Is it due to the proliferation of Spiritual Power or is it due to something else?' Serafall asked herself while gauging the reaction of the Shinigamis, "Of course, there are other forms of power out there, but these are the three most basic ones. Maybe you'll understand it better if I say that Spiritual Power, Magic Power, and Ki correspond to [Individuality], [Reality], and [Ideality] respectively."
At that point, everyone somehow understood Serafall's words. As the people who understood [Individuality] the most, they immediately got an idea of what the other forms of power pertain to. The former members of the Gotei 13 had already set aside the statements made earlier and began contemplating by themselves while manipulating the Magic Power at their fingertips.
And it wasn't just them but also Claire, Kunou, Tanis, and Kisuke who were taken aback at this explanation, 'Wait... I haven't really thought about it, but those are indeed fitting descriptions of these powers.', Kisuke thought to himself. After all, the only thing important to him is how to use said power no matter what form it came in, and never really delved deeper into what they represented, 'Is this what she got when she stepped into the ranks of the Super Devils?'
Without listening any further, Kisuke turned around and started thinking about the current state he was in, 'Unlike the transferring of the soul from a spiritual body to a physical one, my physical body and spiritual body are technically fused together by the Hougyoku. Due to that, I was able to fuse and use Reiatsu and Ki as one. Thinking about it, the concept behind my advanced Shunko might have been impossible if not for this. Both Yoruichi and Soifon-san use an elemental factor to realize their Shunko while I use Benihime's power to realize mine...'
Serafall peeked at Kisuke who was leaving but didn't do anything else to stop him and just continued her lesson, "That's the basic concept. You already learned how to feel and use Magic Power so now we'll show you how to feel and use Ki..."