Apologies in advance for the huge wall of text...
Man, what a great start to a game. I have probably played more AVNs than I should and if this first release is any indication of the future of this title, I think I'd place it at the very top tier. So much so that I'm going to put it in my signature after making this comment.
First, the idol manager setup is a home run of an idea. I think as someone else commented on the thread, you'd expect it to be more common in AVNs given how great of a setup it is, but alas, someone had to do it first. At the risk of stating the obvious, I think the reason it makes for such a great story is because it becomes easier to write a diverse set of characters with each girl having their own personality that fits together because they have a shared interest/job, live in the same house, they all know the MC and each other well, etc. and with the MC as their manager there's a real in-world reason for them to get closer over time and develop relationships.
All of that would already be great, but then having the MC be a newbie who works under an older, would-be idol (who also happens to be the best LI in the game thus far and really well written) is just chefs kiss and shows how thoughtful the writing here is. So world building and characterization for this novel score a 10/10 in my book.
On top of that, there's all the attention to detail which comes through in the richness of the menu options (custom fonts and text size, fuck yeah), the little dialog floating explanations on hover, thoughtful e m p h a s i s littered over the text liberally, the rich soundtrack built-in from the very first update... again a 10/10!
Personally I'm a big fan of HS games, but I know is not everyone's cup of tea. I just think it suits the adorable type LIs really well, which again makes it a great choice for this particular game. I guess in the spirit of not being pure hyperbole I guess there are other HS games with a bigger team that can extract even more from these models and those would be 10/10 renders whereas this one is more like a 7/10 on that department.....except the assets seem pretty varied, such as the richly detailed mansion for the girls, the local street with the burger shop, the KBBQ restaurant so I would give another 2 points for all of that, totaling 9/10....plus an extra point for the fact that this is a sole dev on their first AVN wrapping it up neatly at another 10/10.
I played this today after feeling a bit shitty for life reasons that I really wish I wasn't getting bothered by...I went in blind, not knowing what to expect, and for a moment I was transported to another world, feeling blissful, excited about what the next idol was going to look like and how their personality would be, looking forward to making a move on my boss and eager to start on Monday!
Then I came here to say how much I liked it and saw the planned and unplanned tags which literally map almost perfectly 1-to-1 with my interests (as a maledom fan, I don't care about femdom but even that is going to be optional) how kind, considerate and responsive this dev is to everyone's feedback...man, this is almost too good to be true. I know this just launched but I can't wait for the next update already
Finally, to turn this otherwise glowing review into a ever so slightly more balanced one, I agree with whoever said the dialogue could indeed be cut down a little in both the KBBQ scene and the Ruby intro. I think those two were the only clear instances that needed editing, although maybe I would consider cutting down a line or two in the chats with Crystal too. Basically, if it doesn't need to be said to advance the plot or characterization, it can be left out. And one piece of unsolicited advice: you mentioned not knowing how the story is going to end yet, which is understandable given you just started, but I encourage you to write as much of it in advance as you can. We are all just passengers and you are the sole captain. Some of us aren't even paying for the ride! Based on what I could read of your personality in your interactions above, you do come across as self-assured (in the most positive sense) but knowing where you're going is the first step in any journey, and it can get overwhelming when you're 8-9 updates in and every fan is complaining about something different, you're feeling burnt out from working on the project too long, and you still haven't figured out where to take the story... that's when devs quit.
TL;DR this is an outstanding job, eggrik! In my opinion, you should be feeling super proud of yourself for this excellent first entry and if you keep this up I am certain you will be super successful.