Karin brusquely thrust out the item she'd been holding behind her back, a rectangular box adorned with a pink gift bow.
Very kawaii.
Hesitantly, Sakura reached out and took the box from Karin's trembling hands. It was too small to hide in, so, seeing that the precious gift of cardboard offered no tactical stealth advantages whatsoever and was thus only useful for its secondary purpose of storing items, she tentatively lifted the lid and peered inside.
"A brassiere?" Sakura said curiously, taking the article of clothing out of the box and pressing it against her chest. "I dunno how you got my measurements, but they're bound to be out of date by at least a few hours…"
"It's a special bra," Karin explained. "You'll see— onee-sama!?"
Without an ounce of shame, Sakura slipped out of her Hokage robes and eased herself out of her top. Back when she could still squeeze herself into ordinary shop-bought bras, she had always fastened the clasp first and then turned the garment around before settling her breasts properly into the cups, her ample chest making it the easier approach. With help at hand today, however, she chose the pettanko route of snapping the clasp on last.
Karin buried her face in her hands, watching between her splayed fingers as Sakura pressed the cups of her new bra against her massive shoulder boulders. They could barely cover her nipples, but that wasn't what Karin was worried about…
"Well, what are you waiting for?" Sakura asked, glancing over her shoulder. "Help a girl out, would you?"
Both of Sakura's arms were crossed in front of her, her hands occupied holding the bra in place against her chest, while the straps hung loose behind her, poking out from the tight gap between her arms and the sides of her torso.
Ashen-faced, Karin reached out with trembling fingers and fastened the clasps. As she had half expected from the many baths they had shared, her onee-sama showed not the slightest embarrassment at being seen so naked by another girl, and the unwelcome thought that perhaps she was not being seen in a romantic light by her onee-sama crept into her mind.
"They're shrinking!" Sakura shrieked. "Karin!?"
Her chest was deflating rapidly before her eyes, her breasts shrinking and drawing closer to each other to fit inside the cups!
"It's okay, that's supposed to happen, it's the special sealing formula I inscribed into the bra!" Karin said quickly. "I couldn't help noticing when Onee-sama complained about her sore shoulders and having to keep up the Transformation Jutsu all the time, so I made this minimising bra to lighten Onee-sama's load!"
When they reached O-cups, Sakura's breasts at last ceased dwindling away. It was strange feeling; she could still feel all of her immensity in all of its glory beneath the cups, but more than half of the weight was gone, and her full range of motion had returned!
"This is amazing!" Sakura gasped, twirling around to test how well the bra supported sudden movements. "This is perfect! Thank you so—"
"I have another gift for you, onee-sama," Karin said quietly. "This one's a surprise too, so close your eyes, please?"
Sakura closed her eyes. She listened as Karin approached, felt the gentle brush of her breasts as she rose on tiptoe, and then the light touch of fingers as Karin took her wrist and guided her hand to her breast, before letting her own hand wander slowly over Sakura's heart.
"Are you sure?" Sakura said, touched. "You don't have much to begin with—"
"Take them," Karin breathed, and without warning, she pressed her lips against Sakura's. "Ngh~ Ahn~ 🩷!"
A sensual moan escaped their sealed lips as Sakura began the exchange, taking some of Karin's breast chakra in exchange for more of her own, a bit of everything… though no Kekkei Genkai chakra. Hopefully, the Akimichi chakra she had just given her would put a little meat on her scrawny, bony frame…
[Ding! Congratulations to the Host for reobtaining Uzumaki clan breast chakra! Three out of the six chakra types required for the Host's ascension to a higher level of existence have been acquired.]
And just as suddenly as the kiss had happened, Karin drew away and turned around quickly.
Karin refused to let Sakura see her crying face, but even from behind, Sakura could tell the red-haired girl was upset, even though she was now sporting a pair of breasts at least two times her original size. Obviously, she had not obtained what she had wanted from that kiss.
"I hope my birthday gifts keep you safe, Onee-sama," Karin choked out, her shoulders racked by sobs as she stormed out of the Hokage's office. "Sayonara!"
Sakura absentmindedly touched her tingling lips with the tips of her fingers.
What in the world had she done wrong, she wondered in a daze? Had she not lived long enough as a girl by now to make some sense of these impossible little mind games? Even though she possessed the heart of a young maiden in love where Naruto and Sasuke were concerned, as someone who had never once won a girl's affection in her previous life, she remained, in such matters, a little slow on the uptake when it came to the workings of a girl's heart.
[Status: 34 W-cup (144 cm) -> 34 W-cup (143 cm)]
…
Karin ran out of the Hokage Residence, her small D-cups bouncing wildly as she wailed into her elbow. Ignoring the strange looks being shot her way, she ducked into an abandoned alleyway and slammed her back against the wall of a newly constructed building, before sliding to the ground, hugging her knees to her chest.
"I didn't want your stupid breasts, stupid Onee-sama… hic!" Karin wept, hiccoughing as she spoke to herself. "I know I said I would hear your answer after the war… sniff… but I just wanted to hear you say… I love you! Hic."
The truth was that Karin had not placed her hand on Sakura's chest merely to grope her, but to measure her pulse. To her dismay, the rhythm of Sakura's heartbeat had scarcely changed throughout the entire exchange, which to her mind, could only mean that she did not return her feelings.
After all, one's heart does not flutter doki-doki for someone one does not love, and yet the absurd truth was that there was simply too much fatty and glandular tissue covering Sakura's ribcage, making it impossible for Karin to read her heartbeat accurately to begin with. As a certified medic, Karin should have known this, but the knowledge had conveniently flown right out of her head during that brain-melting kiss.