Chapter Text
Rin rubbed her temples as she actually considered it. She was going to grow a p-penis.
The mere thought of going through with it still felt ridiculous.
But she needed an edge for the coming grail war. In just two months' time, it would begin. Nearly five decades too soon but it would begin nonetheless. It was only by chance she learned of it too, thanks to Kirei of all people.
She had decided to vent some frustration and demanded a spar from her guardian. During said spar, the command seals he possessed as the overseer flashed. He couldn’t ignore that and after she pestered him enough he told her the Einzburn had summoned Berserker a full two months early.
The cheaters.
But still what kind of monster did they make to be able to support Berserker of all Servants with only minor support from the grail? With her reserves, she could possibly manage one of the other classes of Servant… but it would cripple her ability to perform magecraft as the lion's share of her magical energy would go to the Servant.
Still, it was a boon to learn that the war was going to start anyway.
She imagined that the fake priest probably would have thought of telling her only a week at most before the war began to give her as little time as possible to prepare. So she was thankful for that little bit of fortune.
But that led her to her current problem. She had confidence in her skills… but she needed something more… and it required her to grow a set of male genitals.
She rubbed the bridge of her nose and then looked at the assembled regents. She had everything she needed for the potion.
So why was she stalling? Oh, right she didn't want to grow such an organ on her body.
She spent the better part of half an hour staring at the regents and the grimoire holding the instructions.
She then sighed and steeled herself. She was a magus and would do anything to further her research. Even if it meant wounding her pride… and modifying her body.
And so she started to brew the potion that would give her a penis.
As she went through the process of making the potion she thought about why she needed to do this.
Ah, she wanted to make sure she was able to produce more than enough magical energy to supply her Servant and then some. She knew she was likely more than capable normally… but with the war starting early, she felt that something was off and wanted insurance.
Normally she wouldn't resort to this. As she would more than likely just have taken out a loan to purchase more potent jewels… but her bank account was looking rather barren. Thank you, Kirei for your stellar work in draining her family's funds!
At least the bastard helped take care of her mother. It still hurt to see the empty gaze but she was alive.
Thankfully she didn't have to take out a loan as she had stumbled upon one of her ancestors' grimoires while cleaning up that held secret magecraft… but mostly it held specific spells that couldn't be discussed in polite company. She supposed a good place to hide family secrets was in a place no one would expect.
Even if it made it rather awkward to read about all the… lewd spells her family gathered and developed.
But there were more practical spells within one of which she will be using. The jewel studding method.
It allowed a person to generate and store an absolutely ridiculous amount of magical energy… by studding the penis with gems.
The process was actually rather fascinating. It took advantage of the male organs' ability to generate and store magical energy. Which is why she needed to gain one herself.
It was better than any alternate methods she found as this ability was why male mages often were the ones to sell their mana in the form of potions. Other fluids such as blood and breast milk worked as well… but most mages would never let another magus have access to their blood. As for breast milk, that usually required one to be pregnant, and while there were spells to induce it, she imagined it would be a nuisance to manage all the time.
So she chose the jewel studding method.
It was rather simple in the grand scheme of things. One would program a jewel with a spell to do two things. Gather and store magical energy and steadily release a small stream of vitality-tinted energy into the body, specifically to the penis and testicles. This would then create a sort of feedback loop where they would generate more energy only for that energy to be stored and used to further enhance energy production.
There would grow to be an excess that was stored in the jewels that could be drawn upon as if it were the magus natural reserves as the embedded jewels would grow to be considered a part of the body. Doing this bypassed the usual problem with her family's magecraft, which was using up jewels.
Though this would mean she has to polish her non-jewel-based magecraft now that she would have a bit more energy to burn.
But to do this she had to get the prerequisite organ first.
Which led her to the concoction currently brewing.
She followed the instructions to the exact details. She had hoped it would make up for the subpar ingredients. Many of the ones demanded were either too expensive or were now nearly impossible to procure. So she had to improvise. Thankfully the grimoire had a list of acceptable replacements, just with the stipulation that the end result would likely not be as potent.
Which was acceptable to her. She was growing one for more practical reasons… not for pleasure.
After hours of careful brewing, it was done. The ingredients had been rendered down into a glowing pink liquid, just enough for two doses. One to grow the penis and one to remove it.
She would keep it for the duration of the war and then get rid of it, maybe. It depended on how useful the jewel studding method proved to be. She imagined any future relationships would be awkward if she does actually keep it.
But that is a problem for the future.
She bottled her potion and cleaned up the mess. When she finished she took one bottle with her and secured the second in a safe place.
Now she had to get cleaned up herself, she did have school tomorrow.
As she strolled through her empty home she started feeling a bit peckish. She then remembered it was recommended to drink the potion on an empty stomach. So she skipped dinner to proceed with her plan.
She entered the bathroom and stripped. The grimoire said that taking the potion may make a mess so she thought it was best done in the bathroom for easy cleanup. She didn't want her workshop to stink of sweat after all.
She unhooked her bra and let her breasts free with a pleased sigh.
She then shivered as the cool air tickled her fully nude body causing her small pink nipples to pebble slightly.
She should really turn on the heat… but the electricity bill would be murder on her strained finances.
She then shook her head free from thinking about her dwindling savings.
She grabbed the bottle and lifted it to the light. She watched as the sloshing pink liquid glittered.
She took in a breath and muttered, "Time to do this."
She popped the cork and downed the contents. For a moment she waited… and nothing happened.
“Did I mess something u-” her words were cut short as her heart began to hammer in her chest. She clutched her chest as the bottle fell and rolled along the floor.
She breathed deeply as her body began to heat up not unlike when her circuits were running at full blast.
She collapsed to the tiled floor on her hands and knees as sweat began to drip off of her making a small pool beneath her.
Her vision blurred as her body was heating up to the point she let off steam into the cool air.
A moment later an intense burning sensation began at her crotch. A small weight flopped down from her crotch. She looked down and through blurred vision saw a penis… her penis. It was small like that of a child and covered in foreskin. It wasn't just that, as a moment later two more small weights joined it. Her testicles had dropped. They were small smooth and hairless.
As a whole, they looked… kind of cute. But another part felt a bit disappointed at their size.
Her thoughts as a whole all but vanished as the pain worsened… and then it stopped.
Or rather the pain turned into pleasure equal to the pain.
On her arms and knees like an animal, she let out a loud moan, “Fuuuuck!! I- I’m Cumming!!”
Her small childlike penis shot rope after rope of clear seedless cum plastering the floor with clear fluids.
But it wasn't just her penis that came, as a powerful orgasm ripped through her now gushing pussy.
Rin’s face twisted up obscenely as pleasure wracked her body.
After a few minutes of pleasure beyond her comprehension, she collapsed into a pool of her various fluids.
As a whole, it was a sight to behold. The prim and proper school idol was on the floor face down ass up. Her hips twitched and occasionally bucked as a small penis and gushing vagina dripped clear fluids onto the floor.
It was then that the prim and proper school idol and magus heir, Rin Tohsaka, passed out in a pool of her own fluids cumming her brains out.