Now that the final days of the grail war were upon them, Rin was relaxing while reading a book in the living room dressed in her silky pajamas and fluffy slippers, Shirou sat on the table near her, and Saber was in the other room having a snack. But Rin suddenly puts down her book, before looking down toward Shirou and smirks while saying “You know Shirou, you’ve been such a helpful little guy these past few weeks that I think you deserve a reward...”

Upon hearing this, Shirou asks “What kind of reward do you mean? And I just try to be as helpful as I can at this size...”

Rin shakes her head at the tiny mage, before saying “Nonsense! You’re doing plenty to help out! You’re a masterful little foot masseuse... You’re practically the perfect tiny stress toy for my frequently tired feet… And you always seem to show me how to make the best kinds of dishes to eat...”

Shirou scratches his head in response while saying “For the first two, I figure the most I can do at my size is to make you feel a bit more relaxed since you’re on your feet all day. And I’ve always cooked for people, so it wasn’t too challenging to just guide you along...” But then Shirou pauses for a moment, before adding “Not to be pushy Rin, but you still didn’t explain what you planned to do with me...”

Following that, Rin laughs to herself before saying “That’s right... I thought I’d be generous and allow you to stay in my shirt for a little while... What do you say...?”

Shirou begins to blush heavily after hearing that idea, before saying “Well... If you insist Rin, then I won’t exactly complain...”

Rin grins in response, before saying “Aww you look so adorable when you blush like that... And I’m surprised you’re still getting flustered. You’ve basically been my personal tiny buddy these past few weeks. Would you feel more at home if I tossed you into my slippers instead...?” Before Shirou can reply, Rin lifts her legs and plants her slipper-clad feet onto the table, flanking him closely on both sides. And while Rin kept her feet in this position, she rested her elbows on her knees while smiling at him smugly, before saying “You should be well aware by now that these babies are an old well-worn pair, so they are more than able to accommodate you...”

Upon hearing that, Shirou politely smiles and says “It’s not like I’d dislike that, it’s just that I would appreciate a change of pace...” Rin exaggeratedly pouts in response, causing Shirou to shake his head while saying “That doesn’t mean that I don’t think that your feet are wonderful, Rin! It’s just that you already offered the shirt thing...”

Rin begins to giggle after that while shuffling a foot out of its slipper, before gently patting Shirou’s head with her 4th toe. And as she did that, she smiles and says “I was just teasing... I offered my shirt because I thought you earned a change in scenery to what you’ve gotten used to usually...” In response to this, Shirou gives Rin’s toe a brief kiss, wanting to show that he wasn’t bothered by her teasing. And in response to that, Rin reflexively scrunches her toe, causing his body to be tightly smothered against the moderately sweaty and incredibly soft flesh. The smell was practically indescribably for Shirou at this size and distance, and a part of him hopes that he’ll remain at this size for a long time going forward. Rin quickly frees him, before smiling again while shuffling her foot back into her slipper and placing both feet off of the table.

And after that, Rin picks Shirou up, and unbuttons her shirt, revealing a thin black lace bra, leaving him speechless. As he stared at her insanely colossal chest, which was already nicely sized back before he shrunk, Rin smirks and says “Nothing to say, Shirou? Well, I’m going to go over the battle plan with Saber, so you can just enjoy yourself...”

Following that, Rin drops you into the cup of her bra, before sealing you inside and smothering you against her massive breast, and then calling Saber over to start the preparations for the final battles in the grail war...

Now that Saber was in the room, she sits down next to Rin on the couch so they could discuss their plans.

Rin begins, saying “So far, the only enemies we have left are Lancer and Rider. I’m fairly sure that Shinji Matou, a super annoying jerk, is Rider’s master but I don’t know who Lancer’s master is... Which one would you feel better about facing first?” After saying that, she turns to face Saber, causing Shirou to get bounced against the soft flesh of her boob.

Saber replies, saying “Lancer is an opponent who just wishes for a thrilling fight so I can appreciate his straightforwardness. Rider, on the other hand, relies more on catching her opponents off guard with her chain weapons. I’d like to be fully prepared before challenging her.”

Rin nods in response, before saying “That sounds fair. If that’s the plan, then we’ll also need to figure out how to draw one out before the other. I’m sure I could bait Shinji well enough, so would you mind battling Rider first?” After saying this, Rin adjusts her bra, accidentally causing Shirou to roll until landing on her slightly erect nipple. Because of that, Rin quietly yelps to herself, not expecting her tiny mage companion to land so soon on such a sensitive area.

Saber pays it no mind, as she says “If you think that will be for the best, then I will face her with all my strength. When will the battle take place?”

Rin smiles in response, before saying “Probably tomorrow, so make sure you’re well-fed and well rested!”

Saber smiles back, before saying “On my honor as your heroic spirit, I shall indulge to my heart’s content with food...” But then she pauses for a moment, before adding “What about Shirou; if you don’t mind me asking...?”

Rin smirks, while tightly clutching her chest, roughly smothering Shirou against her impressively gigantic breast. After that, she says “I was considering keeping him in my sock as my good luck charm!” Then she raises an eyebrow toward Saber, before adding “Were you starting to miss the little buggy...?”

Saber looks down while blushing slightly while saying “Yes... Would you permit me to keep him in my boot at some time in the future...?”

Rin grins in response while saying “Tell you what, Saber... If you do an awesome job tomorrow, I’ll give you a whole day to do whatever you want with him! And for that entire time, he’ll be the servant and you’ll be the master...”

Saber’s eyes light up at that offer and proposal, causing Shirou to squirm as if asking Rin to reconsider, but she just folds her arms in just the right way to smother him among her breast flesh. And after that, Saber clenches her fist while saying “I’ll make sure to earn that reward Rin! I won’t let you down...”

Following that, Rin starts to walk up to her room, wanting to make a brief phone call while she still had the chance. And during that walk, she peeks into her bra, finding Shirou looking particularly worried. And as if to taunt him, she says “You’re looking quite pale, Shirou... And I too much of a woman for you...?”

Shirou glares back at her, before saying “I trust Saber, but I don’t think giving her that kind of idea is safe for me...”

Rin just giggles, causing her breasts to jiggle as a result, shaking Shirou to his core. And as she giggled, she says “I’m sure you’ll find a way to keep your former Heroic Spirit satisfied...”

After that, she closes back up her bra, before entering her room...

Now that Rin was (mostly) alone, she grabs her phone to call another local to Fuyuki: Sakura Matou...

Upon dialing, Sakura answers, saying “Oh, Rin Tohsaka... Do you need something from me...?

Rin sighs in response, before saying “I know we’re supposed to act like we only know each other from school, but I just have to get this off my chest while I still can...” Right after saying that, Rin starts to scratch at her shirt, pressing Shirou deeply into her boob.

Sakura hums to herself softly, before saying “Alright then, go ahead...” Due to the bluntness of Sakura’s response, Rin instinctively squeezes her chest nervously, continually groping Shirou against the practical sea of soft and slightly moistened flesh.

Rin starts to ruffle her hair in silence, while swaying in place, causing Shirou to be knocked around her still partially erect nipple. After that, she says “I’ll probably be swamped these next few days, and there’s a chance I won’t be around to see you again... At school I mean!”

Sakura calmly replies, saying “I see; go on...”

Rin stomps her foot in an attempt to steel her own resolve, before saying “I just want to say that even though my da—I mean, Dad, wanted you to be a Matou now, you’re still my sister!!”

Sakura’s eyes widen upon hearing that, although Shirou’s eyes widen even further after that bombshell revelation, causing her to say “What did you say, Rin...?”

Rin begins to grumble to herself, still trying to push herself through this highly necessary conversation, before saying “I don’t wanna claim that I knew exactly why Dad needed to do what he did with you and me, but no matter what the world or anybody else thinks; you’re my sister!! And I just want you to know that I love you, and I never stopped loving you as my little sister, even if I had to hide it...”

On the other line, Sakura started to tear up, while saying “I... I don’t know what to say, Rin... I always thought you abandoned me for the sake of both families...” Upon hearing those words, Rin grabs her chest tightly, feeling overcome with guilt while unintentionally burying Shirou against her ample breast.

Rin stamps her foot again, before saying “Screw that! I don’t care about our families or anything else. I’m living my life to my terms now, and nobody’s stopping me! Especially when it comes to my real family... I just… couldn’t bring myself to challenge that before today...”

Sakura eventually composes herself and says “Thank you Rin... Truly...” She pauses for a moment, before adding “But I need to reflect on this. Know that I feel so happy that you still care...”

Rin grins while fighting back a few tears, before saying “Take whatever time you need, Sakura... But just know this: I’m your big sister and if you need help with anything, I’ll come running the Rin way!!”

Following that, Sakura hangs up; leaving Rin to hope that her words had some influence on her long forgotten sister. After that, Rin feels Shirou begin to struggle against her nipple, causing her to bite her lips while reaching to grab him. And once she fishes him out, she glares at him, before saying “And what’s your problem, shrimp...?”

Shirou folds his arms while saying “I was just trying to get your attention...” Then he sighs before adding “So wait, you and Sakura are sisters?? Since when?”

Rin sighs back, before placing him on the bed and sitting on the floor to remain somewhat eye-level with him, before explaining their family history. She explains how their father, Tokyomi Tohsaka, sent Sakura off to be adopted by the Matou family to become their magus. He intended to allow Sakura a chance to become a mage too since apparently only one mage can be raised per family, although she never really understood why. And after his death during the last Holy Grail War, she followed his wishes and avoided her former sister, wanting her to be accepted as a Matou rather than a Tohsaka.

Upon hearing all of that, Shirou slams his fist into the bed, surprising Rin. He explains, saying “That bastard Shinji always bullied and tormented Sakura, but I never interfered because I thought it’d be improper to meddle in their family affairs. But if I knew all of this, then I would have slugged him a long time ago...”

In response to this, Rin’s eyes widened as she shouted, yelling “Shinji did what to Sakura???” Because of the intensity of her scream, Shirou was launched backward toward one of her dirty gym socks that she left on the bed. And as he struggled among the sweat soaked and smelly mass of cotton fabric, the heavy odor overwhelmed his senses as he was swiftly reminded of his many bouts in those socks while she seriously worked over their few weeks together. The craziest part to him was that it only made him want to be cruelly jammed back into those socks for another tough workout, which made him wonder just how many different things awakened in him after all the shrinking. His introspection was broken, as Rin giggles before saying “Sorry about that Shirou... I never realized Shinji treated her like that...”

And after that, she helps Shirou free, before placing him back in front of her and saying “With that bit of information, I’m definitely gonna destroy that guy tomorrow. He’s gonna wish he was never born...” While Shirou was usually the type who wanted to see everyone around him safe and saved, he could make an exception in this case, although he further rationalizes it since he couldn’t help Shinji even if he tried his hardest due to his current size.

Now that Rin had a deep personal motivation to pummel Shinji, she prepares to lure him out so she could pay him back for all the hell he undoubtedly put Sakura through over the years...

Shirou was curious, so he asks “How do you plan to get Shinji to fight you one-on-one?”

Rin smirks and says “I’ll just use my womanly charms...” She winks and sticks her tongue out sexily after saying that, before suddenly shivering to herself, while saying “The thought of even pretending to be interested in that slimeball almost makes me want to hurl...”

But then she looks down at Shirou with a highly mischievous expression, causing him to say “I don’t like that look… Why do I have a bad feeling about this...?”

Rin smiles back while saying “Probably because you’ve got good survival instincts, Shirou... Since I’m gonna feel quite literally repulsed by what I need to do, even if it’s just over text, I think I’ll need you to help me through it...” Shirou starts to back away, but Rin snatches him up before he could get far, before opening her waistband with her free hand. Upon doing that, she grins while saying “With this task, I’m gonna need lots of support, and I can’t think of a better spot to give me all the moral support I need...”

And without another word, she drops Shirou, causing him to fall straight past her waistband right toward her waiting vagina...