This is a story two pack: Shrink on Demand, Shrink on Demand 2: Fun by the Pool
 
Shrink on Demand synopsis:
 
Late one night, Jenna finds an app from a company called BodyHack Inc. that promises to give its users an erotic, shrinking experience. Not believing it's legitimate, she presses buttons without thinking, entering in parameters for the shrink ray. Weeks later, a Shrink Agent is dispatched to play with her, and what ensues is a game of cat and mouse where Jenna is constantly shrinking at work--and constantly feeling aroused. Can she get home and escape the Agent's 'game' to capture her?

Contains: (Shrinking woman)
 
Shrink on Demand 2: Fun by the Pool synopsis:
 
Same app, different girls!

Kaylie always wanted to try the BodyHack app but never had the courage to use it on herself. But after a day of drinking by the pool, she works up the courage to try it on her best friend Cindy!

But she fails to read the fine print—BodyHack Inc. will do the same thing to YOU if the app is abused. Now, both girls are shrinking and they can’t seem to shake the arousal . . .

Contains: (shrinking women)