Sakura woke up screaming.
"Give me a hand! She's going to wreck the carriage at this rate! Damn it, she's just as strong as that woman!"
She felt hands close around her wrists and ankles, and instinctively she began struggling even harder, feeling the heel of her foot connect with something hard. A familiar voice gave a sharp "Oof!" followed by the vivid crack of splintering wood and the panicked whinnying of horses.
"Sakura-chan, it's me, Naruto!" shouted Naruto. "Calm down, everything's okay, you know!"
Her eyes, which had already been wide open from the moment she awakened, finally began to take in her surroundings. She was in a carriage, and judging by the snow swirling outside, she was no longer in the capital. Naruto was looking over her in concern, and Jiraiya's legs were sticking out of the wall in front of her; she had apparently kicked him straight through the front of the carriage.
"Wha—" Sakura said hoarsely. "What happened?"
She was having trouble breathing. It felt as though there were boulders on her chest compressing her ribcage, but no matter how she looked at her cleavage, her breasts were still the same size as before, if only a little bit bigger than usual.
"That's what I was hoping you'd tell us," came Jiraiya's muffled voice, as he extricated himself from the wall. Cold wind rushed inside the carriage through the hole, making Sakura shiver. "What was that Akatsuki fellow's name again? Hidan? When we returned to the palace, we found you unconscious and him scattered across the room in too many pieces to count."
Somehow, Hidan had survived his ordeal, and by the time Naruto and Jiraiya entered the women's toilet, they had found him using his tongue to nudge his head across the toilet's floor towards Sakura, visibly intent on gnawing at her ankles until she died.
"What do you mean, returned to the palace?" Sakura asked weakly. "When did you leave?"
Naruto and Jiraiya shared a meaningful master-disciple look.
"The Hidden Leaf's just up ahead," said Jiraiya, crossing his arms. "You'll hear all about it when we report to Tsunade."
A gloomy silence settled over the three as their carriage completed the final leg of the journey home. Sakura propped herself on her elbows and tried to sit up, only to find that she could not even lift her own weight.
"That cursed technique…" Sakura muttered to herself. "Seems like the blowback is pretty severe…"
…
Long before the descent of the Ōtsutsuki and the advent of chakra, humanity had already developed many means to kill each other through either mundane or supernatural means.
Honoured Sages and the Holy Miko: Those who leverage their spiritual energy to manipulate the forces of nature. They are best represented by the EARTH (☷) Trigram of pure yin, harmonising their spiritual energy with the breath of the planet to provoke mystical phenomena.
Martial Artists and Samurai: Those who flex their pure physical energy to beat their foes. They are best represented by the HEAVEN (☰) Trigram of pure yang, cultivating their muscles and vitality beyond that of ordinary people.
Jujutsu Sorcerers: Those who wield their spiritual energy to curse themselves and their enemies and make their physical energy wither from within. They are best represented by the WATER (☵) Trigram, using imagination from without to affect their target's vitality from within.
The main difference between chakra-wielding shinobi and those ancient professions is how their supernatural abilities come about:
After having been shown how to do so, shinobi can instinctively learn how to crash their spiritual (yin) energy against their physical (yang) energy to mould chakra, at which point they gain the ability to use the five elements (fire, wind, lightning, earth, and water). The opposite is true for those earlier professions; they start from the Five Elements and Eight Trigrams and work their way back from there to obtain their supernatural powers.
So, to recap, shinobi rely on the teachings of the Tai'in Taikyokuzu, the Yin-Yang Moon Diagram, to knead chakra and then derive the Five Elements, but ancient professions rely on combining the Five Elements themselves to obtain yin yang powers akin to chakra.
Jujutsu: Thousand-Armed Deprivation Grudge Manifestation is the name of the cursed technique the system had derived for Sakura. Cursed techniques rely on the ancient principle of sympatheticity: to affect a larger thing by first influencing a smaller representation of it.
In this case, Sakura curses herself lightly so as to curse her target with far greater force, much as Hidan might deliberately wound himself to sacrifice the one he has marked. The nature of Sakura's curse lies in the weight of negative emotions: in exchange for summoning an unstoppable avatar capable of manipulating gravity— one that embodies the hatred of those who have lost their breasts— the apparent weight of Sakura's own breasts is multiplied a hundredfold for a hundred times the duration of the summon.
Of course, it was all in Sakura's head.
Her breasts weighed 9.5 kg (21 lbs) in total, yet to her, it felt as though she were carrying nearly a metric ton across her chest! Otherwise, if they truly weighed that much, they would have popped off her chest.
…
"Come on, what are you doing in there?" Jiraiya asked impatiently, turning to see why Sakura was taking so long to get out of the carriage. "We're already at the Hidden Leaf Village. Get out, will you? Tsunade's waiting for us."
"Yoisho~tto!"
Sakura heaved with all her might, infusing her back and limbs with enough chakra to hurl boulders, and at last she managed to rise to her feet. With shaky legs, she placed one foot before the other… and with a full-powered stomp, smashed straight through the floor, toppling headfirst out of the carriage and getting her head stuck between her boobs as she landed in the snow.
"A little help, please?" Sakura's muffled voice called from her cleavage. "Hellooo? Anyone there?"
Naruto and Jiraiya shared a helpless look…
…and five minutes later, Naruto was carrying Sakura on his shoulders through the village, biting his tongue as hard as he could to ignore the divine softness pressing in against his head, desperate to spare himself the embarrassment of the villagers seeing his little Naruto-kun in his trousers standing to attention.