"This pretty little girl... is actually a middle-aged man with a wife and kids!?"
Gregory, a sales manager at the major pharmaceutical company Dokuryu Group, accidentally transforms himself, along with the Chairman and the Executive Director, into "cute girls" after trying out a newly developed energy drink!
If he can't change back, he’ll lose his beloved wife and daughter—a future he simply cannot accept! To find a solution, Gregory signs a contract with the company to fully cooperate with their "Girlification Research" using his own body as the test subject.
Rejuvenation? Girlification? At least... he can eat all the fried food he wants! In a research lab filled with the dreams and desires of middle-aged guys, will they ever find a way to return to their original selves?
(Source: Jumptoon, translated)
— Description from AniList community (anilist.co).