Magic Circuits are acquired at birth. Though, they are not present in most humans. In Shinji's world, only a select few has it, which is good since it'll be detrimental to the remaining mysteries for the magi to grow in huge numbers.
Since it's located right between the body and the soul, it is termed as a pseudo-nervous system; hence its other name, "Nerve Circuits".
As for the methods of awakening, there are quite a few. But, what Shiro had used is inputting mana inside the circuit, which will cause it to start producing od. With it, they can now be classified as a magus.
By using mana, the environment's energy, and od, the innate magical energy produced by the circuits, it allows a magus to cast their magecraft.
"Hot!"
The method that Shiro used is to stimulate the circuits using his mana, making them think that they're already "producing" od; thus the mana production was kickstarted.
Meanwhile, Sayaka truly felt like dipping herself on a boiling hot water, but the hotness that she felt is inside her entire body. Her skin became reddish and hot to touch while thin white smoke came out of it. Buckets of sweat made her school uniform stick in her skin.
"Kuh..!"
She gritted her teeth, not allowing her painful grunts to be fully heard.
On the side, Madoka looked at her best friend worriedly. She experienced the awakening of Magic Circuits first-hand, so she knows how painful it is. Her unbelievably strong resolve to help others is the only reason why she managed to withstand it.
As for Sayaka, it is her heart of justice. Her willingness to help others is just as strong as Madoka's. What's more, Sayaka prioritized Madoka's safety first.
With this power, she would be able to help one of her best friends at crucial moments.
Light green circuits glowed beneath her clothes, in which it extended from her right hand up to her neck.
'How is this semblance possible?!' Shiro inwardly complained. 'A justice head that has her own Magic Circuits awakened... She's the same as him.'
In the end, he could only ask, "Are you his little sister?"
Hearing this, Sayaka forgot the pain that she's feeling. That's how dumbfounded she is.
Shiro only shook her head and urged her to focus.
"Nevermind. Focus in this first. You'll have to deactivate your circuits first."
"How..?" She replied while gritting her teeth. A few drops of tears came from her eyes—signifying how this awakening isn't for normal girls like her.
"You have to imagine something. A gun being fired, a glass shattering into pieces... Anything would do."
At that moment, her eyes shone brightly as a mental image came into her mind.
Clink-!
Coincidentally, it is the image of a katana being sheathed. If Shiro knew about this, he wouldn't know how to react and instead bring her to Chaldea.
'I wonder what'll happen if these two meets. This will be really interesting...'
After a while, her circuits stopped glowing while her body temperature slowly returned back to normal. Still, the sticky and uncomfortable feeling is there.
"You should go take a bath first. We'll talk about the future training later."
Just as he talked with Madoka and acknowledged her resolve, he decided to train them in his free time. He taught Madoka some combat styles as a magus while he taught Sayaka how to wield a 'sword' properly—the rod that she's been using has the same reach as a normal sword, so he decided to go with it.
This is also the reason why he's close enough to be considered as their friend.
"Alright, sensei~!" Sayaka cheerfully said.
Chuckling, he replied, "I guess you two can be my students too."
*****
In a large city like Mitakihara, there's only a few Witches present, numbering less than 150. They either started off as the Witches' minion or... they're a Magical Girl that turned into one.
Hence, the reason why a veteran Magical Girl is responsible for overseeing a large territory such as this city. Tomoe Mami, one of the few veteran Magical Girls with more than 3 year's worth of experience of belt is widely respected by them.
After all, most Magical Girls can't survive for six months due to lack of Grief Seeds or caving in to despair—the eventual realization that a Magical Girl's end is not a good one.
Unfortunately, she doesn't know much things despite being a veteran. She's left in the dark in regards to the truth behind Witches, the real purpose of Magical Girls, and much more. In fact, most Magical Girls are like this, except for a select few who got the confirmation from Kyuubey's mouth.
Mami having such a strong mindset is a given. As for her trying to persuade Sayaka and Madoka for the first few days, it's because of her trust to Kyuubey. Since they're specifically chosen by it, she thought that they have enough talent as one.
Though, she also knew about the dangers of being one, so she decided on letting them have a 'trial' Magical Girl experience until they decide.
That is the case a few days after their fight with Ulla....
Bam-!
A sound of a blunt hammer being bashed to something is made when Madoka casted [Elemental Magecraft: Wind King's Hammer] at a flying traditional television with wings.
Crash-!
It came crashing down from the air, sending it to the place where Mami prepared her strongest attack. Pulling out the ribbon in her upper chest, it became larger and rotated before it turned into a huge silver handgun that has a huge barrel in the center.
"Tiro Finale!"
A bright golden beam came out of it before engulfing the Witch in midair. Shiro, who is watching this, complemented the powers of Magical Girls once more.
'It can be compared to an Anti-Fortress at the very least. But... there's something else in it.' He thought about the 'something' that made her attack more lethal. 'It's a conceptual attack... How terrifying.'
It didn't take long for the labyrinth to collapse, returning the surroundings back to the normal factory. Meanwhile, Sayaka who is fighting with dozens of its minions got surprised.
"It's already over?!" She said.
With no targets left, Sayaka cancelled her [Projection]. For some unknown reason, she is very compatible with swords—something that made Shiro think if she and the other Emiya is related with each other.
Though, it made her [Projection] of swords stronger and easier than the usual. Heck, she only took a few hours to replicate a D+ Noble Phantasm. It's structure, materials, and memories are understood by her. If she has Shirou's broken Reality Marble [Unlimited Blade Works], she would've been able to perfectly replicate it despite the world's suppression!
While this is a different world, it instinctively rejected her creations the way Fate's world did.
"Crap!"
"Sayaka-chan?" Madoka asked.
"I'm late for today! I'm sorry, but let's meet again tomorrow!"
She didn't even hesitate to cast her newly learnt [Reinforcement] with beginner's proficiency to rush straight to Mitakihara General Hospital.
Shiro removed his [Concealment Mask] and looked at Sayaka's disappearing figure on the distance.
He commented, "It's a good thing that she didn't chose to become a Magical Girl."
"Why?"
Madoka asked him with a confused expression.
"Didn't you know? That Kyousuke... They shouldn't have a chance together."
Shocked by what she'd heard, Madoka froze in place while Shiro took out something from his storage. It is none other than the Grief Seed surrounded by bright white flames.
The remaining 'impurities' on the Grief Seed is pitifully small that he's confident that the purification will be done today.
Seeing this, Mami's complex gaze turned into that of anger, looking like she'd been betrayed by the one she trusted the most.
In the end, she could only word out:
"...Are you done with it?"
"Yep." Shiro replied as he started using up more of his mana to make the flames stronger. "And... there we go."
A moment later, all of the dark spots in the gem disappeared, leaving an unblemished crimson sheen on it. Then, it glowed with bright red light that illuminated the dark factory.
*****
A/N: Beep Beep, MC was misled on that one. Shirou's little sister resides in that certain parallel world where there are lolis doing "mana transfer" through kissing. Man, Shirou is so buffed there to the point that he can summon hundreds of thousands of swords when he fought against Angelica in Oath Under Snow...
Fact #78: Based on the anime, it is shown that Mitakihara City has a very high Witch-Magical Girl ratio. In the past, there are actually a balanced ratio between them, but it is due to Mami that most Magical Girls left the City. She's usually hostile to other Magical Girls (except for Sayaka and Madoka who has pure intentions), thus she's left alone to hold the fort. On the other hand, Mami is dubbed as "God of Battle" due to her extremely high rate of exterminating Witches. That's how she managed to handle the entire city alone.
For all the lesbian lolis in prillya, Oath under snow was a pretty f*cking awesome movie
Badass Shirou
For those wondering why Mami died so stupidly, I think the official reason was she was surprised by one of the other girls lost focus then froze up when confronted with death so close. I mean she IS only what 14-15? And to top it all off in my own opinion she is the one with the least amount will power or sturdy mind (you see her 'break' in multiple different scenarios or anime).
Also, confusing as it sounds, mami leans towards the legal justice side, specially those talented newbies with fresh ideals, they are so good at what they do by the book, but weirdly naive about some other things in the society. She can't relate that some magical girls can't perform the same as she do, but has a weird pride about being the only one who can do so. They are weak because they can't do the same thing as me, not because they are the usual and I am the one who is strong, you see the point? It is also this weird sense of pride that led mami to unconsciously let down her guard by thinking that this case is simply the same as usual: Solo some witches, kill some witches, refill used energy. A case of someone pulling a rag under you, it gets worse now that mami finally found some same minded individuals. Another topic though is that sayaka is a vigilante kind of justice side (not batman, but punisher), anything goes as long as the ideal is met which is on sayaka's side, involving innocents (grief seeds/former magical girls) is wrong, (a bad decision according to my past comment), which indirectly tell why she has so low potential as a magical girl, vigilantes are so realist that you don't put vigilante and hope in the same line (except hoping that batman is the last surviving league member). Case point: mami died out of over confidence and the witch made use of it. I mean the witch baited her throughout the episode and mami didn't even notice because she thought it will just be the same as usual and there is some prospects watching over her which she needs to show off her best side.
It's kinda seeing some long time no see relative at work and you show off by doing some work thinking that things will be the same as usual but the boss suddenly shows up and berates you at some little bad things/habits you do at work, and you know it, can't argue back and you're ashamed of it (totally cornered). I don't think this really happens realistically speaking, but you see the context. (Whose boss has the free time to do that anyway?)
@AlmouthyKing Yep, that's how it went. We can see that she's dominating the entire time, but it's all Bebe's plan. As for Mami's character being that complex, it's due to the director. He didn't tell about Mami's death 3 episodes later so he went full throttle just to create her.
Thanks for the chapter!
If Mami is "God of Battle", then why is her death so lame? That caterpillar came to chomp her head and she just stood there doing nothing with a dumbfounded look on her face.
It wasn't explained very well, but for me personally, it's due to her overconfidence at that time. She focused on showing off as a Magical Girl in front of Madoka and Sayaka, which made her less wary and cautious against her enemy. If she's her usual vigilant self, she would've reacted properly to the sudden regeneration of that Witch. Since it's only at this time did she meet new friends who shares the same sentiment as hers (purely protecting others instead of profitting on Grief Seeds), she let her guard down.
PS: Her title "God of Battle" came from the manga, Madoka Magica: The Different Story.
@IdleYoungMaster So it was just her being an idiot throwing her years of experience to waste. Got it.
@Kurumi69 Well, she can't be blamed. She's been alone for years, so she couldn't help but drop her guard when the two came. Her parents are dead while she didn't have any close relatives left.
Shirou's little sister resides in that certain parallel world where there are lolis doing "mana transfer" through kissing.
Pardon?
That's Fate/kaleid liner Prismer Ilya anime.