Don't take the population element as a focus, if you do your looking way too into it. It's not the point of the manga at all it's just setting the scene/whatever the fairy project 'goal' is.
Volume 4 is where that question matters, Volumes 3 hints at things but most moments are mostly fun moments (Volume 1 & 2 fun or setting things up still) or backstories (more Volume 3 has it's fun moments as well) as it goes along. I recommend reading the afterwords in Volume 3 & 4 between chapters they give a lot of context. Volume 4 gets darker due to the character dynamic/situation they want to focus on. I did find some aspects lack. Some serious are fine, some of the darker stuff in Volume 4 do drag on, their fine but not the most amazing. The afterwords 'help' but you can still think oh ok then for the tension, the character dynamics to put them in situations of, or the writing ideas the creator had but some of it does feel rushed or a checkbox sometimes. Some are very checkbox like, but you can tell they tried to work around deadlines or 'how they wanted to portray it' besides how it's written.
As it goes along you see different backstories or more depth in the romantic partners Anzu has. Many fit tropes of the cool guy (even though he ignores most girls but he trusts Anzu), the friend who was overweight but changed and is part of a sports club, the rich guy and his bodyguard (who starts to understand normal people things/live on their level), you have Saki one of Anzu's friends, and a bunch of others along the way from the cool guy (Kazuki)'s sister, mother/father and more.
By Volume 1-3 it's pretty good, by Volume 4 it goes a bit darker and tries to add a bit more to it. The ending possible to predict too. I get why the creator did it as well it suits the character and well even if things change
The project the fairy is part of becomes more clear as things go on, some of their rules, that the fairy Riri has less control than Anzu thinks they do they are a guidance not a controller. They can't overstep some boundaries which in Volume 4 is made clear but only some details of blending in as human happens in Volume 2 or 3, setting Anzu up on some dates or pushing the rich guy, the childhood friend that had a transformation until eventually they all just bond, 2 under Anzu's house due to circumstances. This is all clear by Volume 1 and 2.
So if you think oh no it's about the population limits well in the beginning for setting the scene yeah but as it goes on you can tell especially in the afterwords of the volumes after even certain chapters not just the end of each volume so a lot more behind the scenes is explained 'why' the characters and scenes were presented, cut short or so as they were and why they felt the characters and situations were presented that way.
The concept sure isn't much but the fact they started with 'I got this idea' and to make Anzu not want love, to stand out. I liked that, it's also what drew me to the anime/manga in the first place and kept reading the manga to it's end. Not because 'oh who will she pick' in a reverse harem way even if that is kind of a question the viewer/reader may have.
I think each character gets a time to shine, I think as you read along they have enough details to them in a back story, in a focal chapter or more as each volume goes along. Some can seem like oh just magic at work but then more is revealed.
It's not the best thing in the world but it's very fun to read/watch I found. I haven't read or watched enough shoujo manga or anime yet but of the few I've got into and reading this many of the tropes were made clear. It isn't exactly a parody fully but you can tell some parts are as such because they wanted the character to not just fall in love that easy, be bent by the fairy's goal and the company the fairy works for and why their rules are what they are and why the project and limits they have aren't what they seem as you read on in Volume 4 then the subtle details in Volume 3 but less clear in Volume 1 & 2.
It's a fun read, characters are fun, moments change and flow well. But some are darker for tension or just character goals as it goes on (remembering more from Volume 4 without spoiling).
I wouldn't take the fairy part that seriously as it is just fun moments to enjoy for most of the series of the way Anzu thinks/acts and the guys are there in situations, some reactions to other friends of theirs do come up as well, some funny and serious dialogue surrounding it of them noticing each other years later and the project the fairies have is in the background until Volume 3 & 4 where more is detailed.
It's a fun ride but some parts are a bit off.
