"Doc, wait! Why isn't mom here?"
Judy sighed. "Remember when I said you thew raw magic everywhere like it was out of style? The only reason it didn't have any adverse effect outside of the shrinking of your magical-core is thanks to your mother's quick thinking. Remembering that most of this magic used to be her own core, she used some meditation technics known to help magical-girls absorb the fundamental components of magic, to grow their magical-core. Most battle magical-girls practice it to the point it become second nature to absorb said components, which is also why they're generally more resistant to magical attacks than most, idols includes."
"Anyway, your mother used such a meditation technic to actively absorb all the raw magic you threw around before it could engender anyone, causing her long lost core to reform. Alas, it's still more magic than a lone person can ever hope to stock in their body, even with a magical-core compressed to the max. Because of this, it became extremely cold around her, to the point very few can go near your mom and survive, even among ice-powered magical-girls. We were forced to place her into a magic-proof room for everyone's security."
As soon as Dr. Hall finished speaking, I jumped out of bed and, before anyone could even try to stop me, ran. I could feel something in me indicating my mom's direction, not realizing it was my magical core, or what was left of it, wanting to be reunited with what used to be part of it. It didn't take me long to reach her room, easily dodging anyone in my path. I got there just as another ice-powered magical-girl got out of the airlock protecting the entrance of the room. I slipped past her, and was hit by the cold. Nothing deadly yet, not if I got out fast enough at least.
The other magical girl was about to forcefully remove me, but my magic-starved core started absorbing the ambient magic and, probably to protect me, triggered my transformation into my magical-girl form. This time I was perfectly aware of my new body shape, but it somehow felt just as comfortable as my usual, male form.
Looking at the door to my mom's room proper, I saw it was locked behind a keypad. Looking back at the other magical-girl, who I discovered was looking at me with her mouth open and eyes the size of dinner plates, I asked "Excuse me, could I… ?" But I couldn't finish my question, interrupted by a loud "EEeeeeeeeeeeeeee! SO CUTE!" while suddenly finding myself engulfed in a suffocating hug.
When she finally let me breath again she started rambling. "I love how you successfully got your own style while still looking like your predecessor! You know she used to teach me before she lost her powers trying to protect her son? I never expected to see her in magical form ever again, and after so long I had lost all hope to ever see someone inheriting her legacy. But here we are, with not only you holding her legacy, but her somehow regaining her powers, all in the same day. Cool, no?! You're lucky in that regard, few can meet their predecessor, and it usually involve time-travel shenanigan, which is rather infrequent alas. Not that it's a bad thing, it's always such a headache to not cause any problem with time-traveling… Anyway, with the others we kept relaying ourselves to search for you. Your predecessor need your help before she can go out of that room without freezing the life out of everyone. The code is her son's birth-year. Do you know when… ?"
"Yeah, I remember when I was born." I exasperatedly interrupted, thinking I know I have a hard time remembering dates, but not to that point. Seeing she hadn't got out nor closed the door out of the airlock, I asked "Don't you have something else to do?" But all she did was look at me, seemingly not understanding, her head inclined on the side.
It prompted a voice from inside the room, to scream "SLICKY!!! She can't enter unless you close the other door, and we don't want you to interrupt their tearful reunion with your usual nonsense! SCRAM!!!" All that was heard as an answer was a sad "Aw…" from the airhead, who still got out and closed the door.
As I entered the room, I immediately zeroed on my mother. She looked nothing like her usual self, but was still able to recognize her thanks to my magical-core calling out to her own. She had long flowing black hairs, with an ice-blue strand on the left of her face, ice-blue cat-like eyes, a voluptuous chest and ass separated by a thin waist, long nails painted ice-blue, thin arms and long legs, all that covered in clothing more expected on a demoness than a magical-girl. I mean, a sleeveless, legless black leather body-suite, with a zipper on the front not only opened enough to give a deep neckline, but was even long enough to even open in front of her crotch, clearly no bra (but the breasts somehow still maintained) and leather boots stopping below her knees with an ice-blue edge. (Thankfully, said boots had flat soles, which is better for a battle magical-girl who need to run, jump and fight in them.)
But none of that was important right now. I was finally reunited with my mother, which somehow caused me to turn into a little girl, mentally speaking. I ran and tackle-hugged her screaming "MOMMY!!!" causing her to fall on her ass.
"Mommy?!?" Wondered aloud one of the other magical-girls present. "I thought you only had two sons?"
"I did, but then someone attacked me in front of my oldest, and he somehow turned into my daughter." Having, by now, recovered enough to participate in the conversation, I added "Only when in magical form. When I woke up I was back to my usual self."
At this mom shook me lightly and asked. "Yuki, do you think of yourself as male or female?"
Mom called me Yuki, acknowledged it as my name. It may not be the one I was given at birth, but it was the one I inherited with her core, our shared name as magical-girls. It made me happy. I knew if I was called the same in my other form I would hate it, but that apply to any magical-girl. We all prefer to be called by our magical-girl name while in our magical form, but prefer our birth-name in our birth-body.
Once I digested the joy of being called Yuki in magical form, I started to think on mom's question. Earlier this morning, I just felt like I always did, perfectly happy with my male body. But changing into a girl didn't bring any sense of wrongness with my body. If anything, it was like a slight change in my mind was operated with my transformation. Nothing drastic, I was still me. Just me as a girl. Not only in body, but also in mind. I'm a ‘he’ in my everyday life, but a ‘she’ as a magical-girl.
After my long reflection, I said as much. "Depend on the form. This morning I was a boy, body and mind. But right now I think of myself as a girl, and I'm fine with it."
Feeling sleepy, I looked around for a bed, before remembering the room was so cold it would make anything brittle. In fact, the only thing that prevented our uniforms to turn into icy dust was the fact they are made of our magic. In the end I fell asleep still hugging mom, my head falling on her shoulder.