[Bimbofication, Gyaru, Incest]

The Holy Grail War. A contest between Maguses with the most valuable prize for the winner. A single wish, fueled by the souls of the heroes summoned to fight in this war. It’s a tragic affair, one that many would scoff at due to the dangers involved. And if they knew about the secrets of the war and why it functioned the way that it did, they’d no doubt condemn it harder.

But for those that wanted to achieve their dreams, in such a desperate fashion, it was their ticket to glory. That was why it had happened five times thus far. And the fifth, though not nearly as destructive as the others, was still a harrowing matter.

In the end, no wish was made. The Holy Grail itself was destroyed to prevent its corruption from seeping out. And as a reward for their selfless deed, they were gifted a life with those that fought at their side.

...Which was exactly why Tohsaka Rin, one of the Masters participating in the fifth war, was currently having a bit of an internal dilemma. Because as it turned out, one of the girls that had been a part of this ordeal was her sister. A sister that had been taken from her when they were young, due to the archaic rules and laws of the world of Magic.

To say that Matou Sakura, the sister in question, was not pleased with this arrangement? That was an understatement. And to think she had been keeping those feelings pinned down inside her heart for so long. As her older sister, it was up to Rin to do something to fix their relationship. A show of affection, to show that she meant no ill will.

Unfortunately, asking this of Rin was a bit… difficult. Especially since she had not spent a lot of time together with the girl, since she seemed to be close to Emiya rather than anybody else. And she had only started to get close to that reckless self-sacrificing idiot during the war...

“What does a girl like Sakura even like…” The brown-haired Magus muttered as she paced back and forth inside her room, smoke slowly pouring out of her ears. She thought long and hard about it, furrowing her brow.

She could go for the safe option. And get her something that Emiya would enjoy. But that would imply that she thought of her as just another version of that boy. So she had to think of something unique to the girl…

It didn’t take long for Rin to eventually just collapse onto her bed, the steam pouring out of her ears. “Ahhh! I can’t see through that girl, and yet she knew exactly what I wanted!” She shouted into the ceiling, her head slowly turning towards the gem on the nightstand. A pink little jewel, intended to be used for high-level magecraft. And a pretty gift in general. That was what Sakura had given her to try and make amends.

...Hold on just a moment. She gave her that jewel. So she intended for her to use it. Would the best gift not be to use it to do something for her? Of course, then there was the matter of what to cast exactly, but…

Rin smiled a little as her eyes lit up, grabbing the jewel as she stared straight into it. It was extremely reflective, to the point where the slightest bit of light was enough to reflect off it and nearly blind the girl, but that didn’t matter. Because she had the best, nay, the most amazing idea.

With jewel in hand, the brown-haired Magus took off. Heading straight for the Emiya residence, knowing that her sister would be there.

---

“Rin? Have you seen Shirou?”

The brown-haired girl twitched a little as she heard Sakura’s voice. She had made the right call, the girl was exactly where she expected her to be. She just forgot all about the girl’s near-obsession with the boy that had done plenty for both of them.

“He’s probably training with Saber. I didn’t see him on the way, at least.” Rin said as she quietly stepped further inside, casting a glance at the purple-haired girl standing in the kitchen.

Matou Sakura. Her sister by birth, torn from her when they were young. And yet despite everything she had gone through at the hand of the man who headed that family… She was still able to smile. Even though she should’ve been broken by that treatment. Even though she had all the right in the world to tear the people around her to shreds. It was thanks to the efforts of Emiya Shirou that she could smile without worrying… That boy had really done a lot for her. And for Rin as well, considering his hand in dismantling the grail on top of all that.

And it was honestly pleasant seeing how far she had gone since then. A girl who should’ve been broken, now standing inside the kitchen wearing an apron and carefully preparing a big meal for her beloved. Like she had been dealt the best possible hand in life.

“I see… Well, I hope he’ll be back in time for dinner then. I’m making an extra large portion to make sure Saber doesn’t eat it all either.” Sakura chimed as she slowly leaned against the counter, before sighing and looking directly into Rin’s eyes. “Now… Why would you come by, if he’s not here?”

Rin twitched a little. She could feel those sharp eyes. If there was one thing that hadn’t disappeared after the war, it was her sister’s chilling glares. It was something she had perfected while she was serving as an enemy in the war. And she used it to great effect to cast blame on her for what their father had done.

But she couldn’t back down in the face of mockery. Otherwise their relationship wouldn’t be mended.

“You gave me this, remember?” Rin said as she pulled out the pink jewel that immediately started to shine as the light above reflected off it. “I just wanted to show you what I could do with it. Consider it my gift to you.”

Sakura shook her head slightly when faced with her sister’s proud smile. “Rin, you weren’t meant to use it for a spell. It’s supposed to just be a gift you cherish.” She said, before giggling a little. “But I guess that’s just like you. So? What’s the spell?” She wasn’t too hurt by this turn of events, and more just curious about what her sister could pull off. There were a lot of things you could use gems for, especially considering the Tohsaka family’s gem-fueled magecraft.

“It’ll amaze you, that’s all I’ll say.” Rin lied through her teeth. She didn’t know what she was going to cast, but she had gotten this far. Surely just pouring a bit of mana into the gem couldn’t do anything bad, right?

The brown-haired Magus did just that, her magic circuits letting her mana flow into her fingertips, as the pink jewel started to glow even brighter. Brighter yet brighter, until the light had completely consumed the living room, and both girls with it…

Sakura could feel her shirt growing tighter as the light washed over her. But her thoughts were scattered. She couldn’t say anything to stop her sister from pouring mana into the jewel. And why would she, when it felt real nice to just stand there and look into the pretty light?

Rin was in a similar situation. She had been staring straight into the jewel as it started taking in her mana, which made it incredibly difficult for her to see how it kept slurping up more and more of it. If she had bothered to check out what kind of jewel it really was, she would’ve realized that it had anti-Magus properties. It would absorb all the mana of the Magus who tried to use it for Magecraft, and then convert it all into something much more appropriate.

Both sisters were just standing there, watching the pretty jewel glow brighter and brighter as its light washed over them. And from that light, it poured the converted mana into them, to cast the ‘spell’ that laid at its core.

Sakura’s breasts burst free from her conservative top for a brief moment, both of them bouncing bountifully before they were pressed back against her chest thanks to the swift intervention of a knot tying both halves of her flimsy shirt together. Or rather, the cloth that had been wrapped around her back before being tied together right in front of her big melons. The light had managed to change her outfit into something a lot more scandalous, and it had only just begun.

Her skirt and her stockings, something intended to show modesty, were twisted into a set of torn leggings that showed off plenty of skin, and a pair of short shorts that were struggling to keep the baggage within properly pinned. As a result, the mere act of breathing was enough to make the purple-haired girl’s derriere wobble up and down like the most jiggly jello imaginable.

With her clothes changed, it was time for her body. While her assets were ample and already emphasized by her new slutty outfit, she didn’t stand out quite as much as the jewel wanted. Thus the mana-filled light sank into her skin, dyeing it a nice shade of brown to make it look like she had gained a pleasant tan, as the roots of her hair turned nice and blonde to match the look. She didn’t need to look traditional at all, just a good trashy gyaru willing to show it all off.

Rin was getting her own dose of that mana-fueled light, her skin having turned a deeper shade of brown due to her mana being the fuel for the jewel’s spell. Her hair met a similar fate, though her blonde shade seemed a little fake compared to her sister’s. Like she had gone overboard with both the tan and the hair dye, to the point where she looked like an exaggerated parody of a gyaru.

The changes done to her outfit didn’t help matters. While her sister had the nice tied top that brought emphasis to her tits, the former brunette didn’t even need a top. Her red shirt shrunk until there were barely a couple of strings left, leaving her nipples almost completely uncovered as they started to grow erect from the warmth washing over her.

Her skirt faired a bit better, as it merely grew shorter. But that’s all that the girl wore. A painfully short skirt, no stockings, no panties, nothing. She was letting it all hang out for the public to see. Whether it was her modest bosom, or her impressive hips and ass. The only thing she needed to go from Gyaru to Ganguro was an additional layer of makeup, but the jewel wasn’t going to go that far. Since it was about to run out of Mana.

Once the light faded and the jewel harmlessly landed in the older sister’s palm, the two girls blinked a couple of times as their minds started to catch up with their bodies. Anybody would be confused if they were faced with such a drastic change...

“Like… Rinny?” But that would imply the jewel hadn’t affected them mentally either. Why would they think there was anything wrong with their bodies, if they thought they had been this way for years?”

Rin stretched a little, her string-covered tits bouncing in the process. “Mmmmmhm, Sa-sa?” She asked, the heat still flowing through her. She really needed something to quench that thirst inside her, and fast… Otherwise she might just…

“You’re like, super hot…” Sakura said as the gyarufied girl stepped closer to her deep-fried sister, her heart pounding against her chest. Just looking at the other girl was enough to make her head swim…

The former brunette looked at her sister, and she couldn’t stop herself from giggling as she held her arms out as wide as she could. All doubts had vanished from her mind, replaced with nothing but lust for her sister.

A feeling the other girl shared as she buried her face in the older girl’s tits, panting as she rubbed her body up against her older sister’s. A passionate gesture that the former brunette returned, rubbing back with just as much vigor. A bit of foreplay, to rile them up before the real fun began...

This would be Rin’s gift to Sakura. A mended relationship. Just not in the way either of them could’ve anticipated...