This is kind of a cute/ecchi manga. But the main MC finds a tree that he's able to pick the fruits of that has a "Rejuvenation Apple" and "Child Apple" that decreases the targets age by 1 and the other, decreases age by like 5. As a result he has a quick fantasy about his slaves as young girls, he also has one of them older as well. Since in the manga/LN they're technically only 16. We'll see a TG later in this Manga, as I've read the light novel as well. But it won't be for a while. Manga and LN, he says HE'D take the child fruit, but Manga shows the two slaves he has as slightly older.
https://mangarock.com/manga/mrs-serie-100077695 chapter 25