TD; DR:
(+)(+)(+)(+)This is a fantastical, beautiful, gripping tale with so many layers and content, easily digestible, and NO overcomplicated system for how many paths you have to unlock and items found before you get to see the "true end". It is a nice mix of politics, crime, personal trauma and romance.
So much heart also for the artistic details and variety. Many different locations, items and CGs are presented. Each of the key figure characters has multiple expressions - not only the MCs.
I had a lot of fun and will keep my eye out for any future projects! <3

(-)There are a few barely noticeable sound and navigation things; I personally would have preferred another way.
Instructions were not clear (for me ;P). I often felt indirectly animated by the game to analyse the clues immediately, even though you were NOT actually meant to guess along but just to go with the flow and accept it as something that would feed later into the romance story in some way.

The loooong review:

Soooo. I finished my first playthrough (minus the bonus(?) ML POV  - I'm a bit too tired rn, but I will do that a later day). And I loved it!

The main story is packed. I did not really have a reason to, but I just assumed that I would unlock the individual background from the different key figures and aspects from the overall story in different routes. But after finishing my first run, I feel like now no answers are left open. I like it the way that this game handled it so much better!

I'm really trying hard to not write too spoiler-ish stuff, so I'm a bit limited in what to write.

I really liked the focus on the undercover mission and was blissed out of my mind after realizing that Mai would indeed approach the situation - true to her originally introduced character - with a levelled head and competence.  The only bit dishearting thing (and I categorize it as a 'can't be helped' detail) because of the countdown of the days it was very apparent how long between the initial report of the *coughcoughSPOILERcoughumanSPOILERcoughSPOILERcoughcoughtrafficiingcoughSPOILERcoughcough* to the next clue and the final solution hurt a little bit Mai's reputation as brilliant detective in my eyes. Still competent, though ^^ So it's okay.
I'm not a good judge of romance since the smoother and more experienced the counterpart of the MC is, the more wary I become in the FL stead—like an overprotective bestie ;) So ... yeah. I have issues, and in 90% of cases, I'm wrong. Pacing-wise, I was really smitten with how their dynamic progressed, and the ratio of Mystery/MattersOfTheHeart parts was perfectly measured! Neither got boring or overstayed. I also really appreciate that Mai's personal Arc was not so linear: It had ups and downs, and even the changes she went through were challenged again. This made her journey feel more complex and deeper <3

Anyway, next point: I really enjoyed the execution of the dramatic moments. And I think it says a lot how well written it is when - even when not each twist would be mindboggling unexpected - I still got sweaty hands, and my heart was thumping when it was time for THE REVEAL(s). It was so SO good!!!

the only personal minus points were:

-The music volume level between scenes seemed sometimes drastically louder or quieter

-I would wished for a logg instead of clicking "Back" over and over again to look up a missed line

-This is on me so I won't let it influence my score... But still, it is something that made me confused oftentimes, so I want to mention/warn about it: This is definitely a romance drama, not a detective game. I was often overinvested by the UNKNOWN/mystery/crime-solving aspect. Probably because we perceive the world through Mai's POV, and Mai expresses again & again how the answers are essential for survival. Therefore, I slipped myself into detective mode again and again. And while this visual novel is great in emotional and dramatic scenes, the "mysteries" are more designed to be easy to digest to feed into the overall romance story - and not as an ACTUAL challenge that needs to be conquered by the person before the screen
(For example, Me as a player: "In a condensed game like this every piece of information matters. So now that I know that there is a Strawberry Icetea from Starbucks is in the action... I also know that only one of my 10 purchased drinking items is from Starbucks, and that item is also always and mainly described as damn fruity. Close enough, and case closed!" Meanwhile, any person that would be actually in the situation: So, step one: It's just one singular rumour between thousands of others. Realistically: Do I even need to care at all? Assuming I do care: Now I need to find and check every sold Starbucks drink worldwide...)

In sum, it is a really great entertainment piece made with a lot of heart! Perfect for anyone who wants to get carried away by a dramatic historical romance story:)