Sakura felt frustrated with her progress. She was giving her absolute best in training and in missions, yet she was self aware enough to know the gap between her and her teammates just kept getting bigger. It didn't matter how unfair she thought things could be, how she didn't get a hereditary gift like the Sharingan or an opportunity to summon the power of a demon to her advantage, what mattered is that both Sasuke and Naruto were leaving her in the dust and things weren't looking anywhere close to improving for her.
Her sensei understood her frustration and supported her, but he could only provide platitudes, given how he ended up having a Sharingan for himself too. What did she have going for her? The only areas she seemed to excel were her fine tuned control of chakra and her book smart intelligence, but neither of these qualities were fancy or powerful enough to provide a real difference in battle. The enemies kept getting stronger, more dangerous, and all she could do everytime was watch. It made all her training as a kunoichi look worthless and it made her feel like a sham, and she was sick of tired of it.
So with no real ideas of how to fix this, one day she found herself wasting time in the konoha library and losing track of time consuming information about whatever non fiction text happened to catch her attention. The history of Konoha, the life of the First and Second Hokages, a book about old and forgotten traditions in the village and why they became extinct. In one of those books she found a strange set of scribbles and doodles though, drawings that for the untrained eye looked like nonsense but she could see a pattern, a pattern for.. hand seals? She decided to borrow the book and take it home, just out of sheer curiosity.
After a more exhaustive look she didn't find any reference within the book as for what those hand seals were supposed to stand for, so with no other option and so intrigued by it she decided to give it a try, knowing with her control of chakra she would be able to stop whatever happened and avoid any disaster at home. She performed the hand seals, focused her chakra on her chair and her eyes went wide at what was going on, it was shrinking!
She quickly stopped the jutsu and at first panicked a bit not knowing how to explain this, it wasn't a huge change but the chair was noticeably smaller, to the point she would probably crush it if she sat on it. She looked at the doodles again and found a strange sign that seemed to signal performing the seals in reverse would also do something. She tried it and sure enough, the chair grew back to normal size.
"Could this work on.. I need to try again" Sakura was too invested on this new strange jutsu and made some more experiments, finding how she could shrink things a lot and grow them back to normal size with relative ease, and how she could in theory grow things beyond their original size too but it required quite a bit more chakra than shrinking and restoring the original size. She got a bit anxious with her last attempt, but it needed to be done, so she focused this time on herself and got the surprise of her life when it actually worked, this jutsu even worked on people!
Sakura went to sleep with a smile on her face, feeling her hard work had been rewarded with what seemed an unique power forgotten by everyone. She couldn't wait to try it on her teammates, wondering with a grin how dangerous would Sasuke or Naruto be if they were half her size, toddler size, insect size even.. or how her rival Ino would dare to insult her if Sakura now towered over her.. The possibilities were endless! Despite all her excitement though she was still aware a final test was needed, a final test that required a willing subject. Maybe someone like Rock Lee could help her? She would take her decision the next day, for now all she wanted to do was try to sleep imagining scenarios where her jutsu would show everyone how powerful she really was.
What happens next?