Chibi Effect - Concept Brainstorm...
While initially offered as a prescription drug to help people who are outside the norm (too short or too tall) shed their awkwardness so they can fit in better... the pills quickly turn into a cosmetic and recreational preference drug.
The start of the fad could be men buying the expensive bigger pill.. as mainstream dominant men tend to want to be bigger, and even many women tend to want men bigger than they are.
This leads less economically well off women buy the cheaper 'shrinker pill' to make themselves smaller, to provide the same submissive appeal to men who don't have the money for the bigger pills.... starting the 'Chibi' trend.
These get combined together, as some oversize men become fascinated by the bigger delta between them and smaller Chibi women.. which starts a bit of a social media phenomenon about what couples have the biggest size difference.
Which also starts the counter-culture examples of Chibi men and oversize women, and lesbian Chibi women with oversize women, and wealthy double-oversize couples.
A female main character could start out in the Chibi movement, and even encourage her man to use bigger pills... but as she shrinks and he grows, her smaller size (Especially smaller breasts) lose a bit of their womanly appeal for him, and his interest starts wandering to other women (even oversize women), which his Chibi girl can't exactly get in the way of, because she's been relegated to more of a submissive fashion item than a girlfriend.
While at first she's sort-of into being the Chibi-plaything for her boyfriend and the busty women he attracts...She eventually grows envious, and asks him to help her pay for growth-pills instead. He refuses (they are way too expensive), and he likes the new status-quo of how having a Chibi-girlfriend attracts curious oversize girls for threesomes.
The Chibi main character gets frustrated, and starts seeking out a solution... running across the counter culture of Chibi men and oversize women, and men who will pay to get their women growth pills. Thinking of this as a way out of her predicament, she connects with a man who is looking for a serious relationship with a woman who's okay being bigger than her man (and he'll supply the pills).
On their first data, he's surprised she's a Chibi, and she has to confess the confusing disappointment of her last relationship, and how she thought Chibi would be exciting, but it's just not for her. She's tired of being tiny and taken advantage of. He confirms that she's okay taking bigger-pills if they are dating, and she enthusiastically confirms she would, gladly. They hit it off personally, but at the end of the date, he's really not attracted to her small size and sort-of shuts her down sexually. He is willing to explore a relationship if she's willing to take the oversizer-pills.
They have a set of actually fun dates, where each one starts with an expensive oversizer pill, and then they go have some fun on the town. After a week she's excited to be back to normal, and she wants to take the relationship to the next level. He does too, and explains how much he likes her, and trusts her, and wants to get serious. He drops one bigger-sizer in her glass one smaller-sizer in his and offers her a toast. "Wait, you're going to get smaller too? are you sure?" And he is.
After their dinner date ends, she expects it to end like all the others, but he invites her back to his place... which turns out to be a lavish penthouse apartment... giving her a view into just how wealthy he is. They flirt and drink a little, and have normal size sex, and she stays the night.
In the morning, she crawls out of an empty bed, unable to find her clothes, she borrows one of his shirts, and heads to the kitchen to find he's already made them both breakfast. She flirtatiously gives him a good morning kiss, realizing she's already his height, or maybe a hair taller. She compliments him on 'last night', and the wonderful smelling breakfast, and how 'a girl could get used to this'... and he flirts back about how gorgeous she looks, and invites her to have a seat.
As he sets out the breakfast, there is conspicuously another bigger pill for her and another smaller pill for him. She picks up her pill, and dives right to the chase. How serious is this, really? SHe just got back to near normal, and now he's not only asking her to keep going, he's taking the smaller pills now. Where is this heading for you? Because I'm falling for you, bigtime, but I've been a Chibi and I grew to resent it. Are you sure this is what you want?
"I am absolutely sure." He turns and slides a key across the counter. "I was going to wait a bit longer, but there's no sense anymore. Come live with me. I know we've only just met, but this is very serious for me, and I can't think of a better way to take the next step."
She's elated and blown away, and rushes up to kiss and hug him....