Written for the prompt some time last year: "Sakura gets shrunk down to about 5 inches high when an experiment with Tsunade goes terribly wrong, just before the Rescue Gaara arc. However, she keeps all of her physical strength. AntMan!Sakura."
One morning, when Haruno Sakura woke from troubled dreams, she found herself transformed into a pink ant. Oh, she wasn't truly an ant, she realised after a moment of frantic checking. Ants, she reasoned, could not see in colours. Sakura (currently) only had four limbs, no extra segments, and she was perfectly capable of standing upright. She could reasonably conclude she was not an ant; still pink, but human.
Ontological angst allayed, Sakura now set to assessing her situation. There was a dead worm staring at her in the face, itself squished on a ridged plane. Mountains of papers surrounded her, and nearby was a glass of nauseating clear stuff that she could swim in. Over the window the sun was rising over the great facades of the Hokage past – and truly Sakura had never appreciated their greatness so much as when she was not even fit to be a speck in their eyes.
Most reassuring was the loud, periodic buzz that seemed to fill the room. Sakura found some solace in knowing she was at the same place she had been when she had fallen asleep. An envoy from Cloud had been scheduled for the next day – this day, in fact. Alas, Tsunade had created a massive backlog of her work, so much that only by burning the midnight oil could she be reasonably prepared to entertain the envoy. Enter Sakura, the Hokage's apprentice and sometimes gopher and wrangler in one. While Tsunade had been working Sakura had been tasked with deciphering a technique Tsunade had created while drunk and bored and confined to her desk. Most of Tsunade's drunk creation fizzled into nothing, especially when Sakura had been plied with alcohol as well. It was just a matter of probability that one of them worked on the day Tsunade would be too busy to reverse it.
Right on cue the guard chuunin outside knocked the door, starting Tsunade awake. Startling Tsunade was never a great idea in any case, but Sakura was now facing the prospect of death hitherto unthought of. Being that she was, even she would admit to herself, a decent shinobi, Sakura's reflex acted to save her. While Tsunade mandated evasion tactics for her medic-nin, this one thing stayed with Sakura the most: strike back with greater force.
Her chakra-enhanced fist met with the dead worm with the satisfying sound of bones breaking. The threat was neutralised, yet Sakura could feel only dread. She took a wild leap of faith, with chakra propelling her feet for good measure. Barely a moment passed before Tsunade emitted a paralysing roar. The fist of an angry drunkard descended and broke the earth – or just the Hokage's desk in less dramatic moments – now in splinters gleefully coming for her head, even as the 'earth' was coming to her with open arms.
Well then, Sakura thought, I have always wanted to know if an insect ever fell to its doom. But Sakura was a ninja, and her teachers had trained her too well, and with a little chakra here and there she landed without so much as a ripple, and she still had chakra to spare for the splinters.
But she had no time to breathe. Even as Tsunade grumbles swallowed the other sounds, the sky fell on Sakura one abused boot after another. Twice she nearly met the end of ants, but with judicious use of chakra she evaded them all. And then it was suddenly so quiet she was certain they could hear her tiny heart beating. She heard the thunder rolled, 'damned ninja bugs,' and scurried into the first dark crevice she tripped into.
The space between stone and wood was dark and musty, full of cobwebs and dust, and not a single living being. The commotion faded as, she assumed, the Hokage went to welcome the Cloud diplomat. Here Sakura stopped and pondered her situation. She was not, despite walking and looking like an ant, an ant; she was a ninja of Konoha, and the Hokage's disciple besides. A little size problem should not have invalidated all that. Although sounding like an ant might have been a problem.
Then as suddenly as the clouds sneaking on the sun, the dark corridor no longer felt welcoming. There was neither sound nor movement, yet all her nerves were screaming of danger. The night vision technique activated and intensified, Sakura turned slowly.
The thing was neither dead nor alive. It was bound in the tattered remains of its freedom. Six once nimble legs now barely hung to its body, itself a hollow shell barely holding itself together against the forces of gravity. Sakura was glad for that; the head alone could fit the entire length of her, and she never wanted to see its mandibles in action, each as big and deadly as a horse cleaver. The eyes seemed as though they had been blown off, or chewed out, or both at once.
It was mostly dead, but for the moment it pounced on her with the speed of an angry bee. Here again Sakura's instinct served her and she delivered a solid chakra payload on her right hook, if perhaps excessive for the target. That was a mistake.
Her fist struck, and was stuck. The strange insect did not crumble under the force. On the contrary, it was gaining its footing as more of Sakura's chakra went to it. Sakura drew a kunai with her other hand. It was like trying to fight a tiger with a toothpick, but the kikaichu was still too weak and wary.
She took the chance to disengage, leaping to the wall and running up. She didn't stop until the angry chittering was inaudible, and sure enough, it wasn't strong enough to chase her. She counted it as good fortune. High up there were even more cobwebs, and Sakura was uncomfortably reminded of the ditty about spiders and flies. She thought it was strange she had never heard something similar for Konoha's own signature insect, but she supposed they were too busy hiding behind the Hokage's bookshelf. Sakura saved it for her report to Tsunade later, if her mentor wouldn't have squashed her first for breaking her foot, regardless of whether being ant-sized was enough justification.
Out of curiosity, thoroughly encouraged by her current size, Sakura followed the webbings. She hadn't noticed at first, but they did not look like any of the cobwebs she had battled against in her time serving as the village's contracted janitor, more politely known as genin on D-rank missions. The web mostly went in one direction. Occasionally there were branches to create scaffolding. Even more curious, the other end went to the genjutsu-veiled hole on the wall.
And once she noticed the genjutsu the chakra coating the webbings was all but blaring, enough that she didn't notice the ninja spider and its shot. The sticky web plastered Sakura to the wall. Either chakra or poison paralysed her, if the tightness had not discouraged movements. Sakura caught a glimpse of her attacker, and was slightly disappointed it appeared mostly like a normal spider. A normal spider with too-bright and intelligent eyes and a most ominous stillness. Sakura decided she did not want to know just how clever a ninja spider could be.
Chakra scalpel from her fingers made short work of the web in a wiggle, and the rest was brute force ripping. The spider had disappeared in the mean time – genjutsu again. Unbidden, Sakura found herself thinking of Sasuke and wishing he had been there. The spider's entire schtick would have been a very unsatisfying snack for his fire techniques. But Sasuke was not here. Sakura knew no easy ninjutsu, but she thought even Sasuke would have approved her plan.
She let loose concussive chakra fit to demolish a house on the web. The force reverberated along the network, and there was a moment when it seemed it would snap. Fortunately Sakura was not waiting on that. While the spider was hopefully distracted with not falling to its doom, she threw all the exploding tags in her pouch. Two and microscopic they might be, but each packed the full capacity of human-sized tags.
The explosion was deafening, but the flower that bloomed was pretty to look at. Sakura didn't have time to admire it as a flaming spider came straight for her. She dodged, giving it an extra help to go through the wall. It made a strange sound like iron cutting into iron as it plummeted. And spider silk shot and stuck to Sakura's leg, and she fell with it.
The Hokage's office was the tallest building in the village. The fall wouldn't scratch any genin worth their headband. Sakura wondered what a ninja ant would do. It looked as though she was about to find out if ants would leave a splat on the ground, after all. She had cut the web with chakra scalpel and threw kunai at the spider for good measure. So that left her falling, with all the dizziness and none of the beautiful aerial view of Konoha.
Sakura thought she should be forgiven for not watching her back. Most sane beings would rather not free fall to their doom. The kikaichu jumping after her for a hug squeezed all the air out of Sakura. As a girl Sakura had sometimes dreamed of dying in someone's arms, preferrably Sasuke's, but three times as many pairs seemed overkill. On top of that, her partner in death by gravity was enjoying itself on Sakura's chakra.
Her ears buzzed and visions of black clouded her eyes. She was seeing multiples, dozens of tinier versions of the kikaichu on her back dancing before her. A cloud of kikaichu descended on her and surged from below. Poor buggers, they had a greedy queen, Sakura thought before the last of her strength left her.
When Sakura woke up from a troubled dream of being eaten by insects alive, she woke up in a hospital bed. The Hokage's benevolent face was glowering at her. Sakura had been discovered in front of the Hokage's building, chakra depleted and wholly human. No one noticed how she arrived there. The ANBU had not found neither dead spiders nor the ashes and damages on the wall and bookcase thereof. There was no scroll of shrinking technique. Sakura was tempted to ask about the Hokage's metatarsal bones, but Tsunade was a caged thunderstorm during her short visit, and so she did not.
After, she found that the Cloud envoy had come and gone just as soon. This the Hokage had deemed an insult and a portent, though to date nothing had come out of it. Sakura also ran into Shino, and for the first time in their acquaintance braved herself to ask about his clan's signature bugs. What little of Shino she could see seemed surprised, and he answered laconically, which she took to mean he was not offended. A kikaichu queen was five times the size of the workers and soldiers without any of the bite. Queens were never supposed to leave the Aburame's holdings, and it would be a dead Aburame who lost his queen.
Sakura did not have time or thought to spare for dreams after that. Naruto returned the next day, and with him she was thrown back into reality, that of a world of monsters and anarchists and gods.