TBF I also loved this game and want to buy it whenever DL site lets me but I also was disappointed by the fact that you actually get a choice that's like "choose this for NTR route" on day 3 or w/e. I felt kinda robbed by the fact that the earlier decisions from day 20 to 3 didn't matter nearly as much as I thought.
I would like it if there was a point system and that the bulk of your choices mattered or if you had to actively stop the NTR.
I think actively having to go for the NTR is kinda the lamest way to go.
This is why Karryn's Prison will always be a good game for corruption- it got the corruption right. It should be difficult to avoid at the gameplay level. Here, it's extremely easy to avoid at the gameplay level - you don't need to do anything at all to win EXCEPT not get too intimate with Pink hair- but the game nails it at the narrative level.
I understand your concerns, but it totally felt hella hard to me. I felt like Kurone was affecting my mind as well lol. I went into the game thinking "I'll leave the MC as pure as possible and see how the rest plays out", but I found myself giving in and in more and more as the character's personality, motives and... Tactics, were unveiled. After some time I was completely invested, wished to see if she could get a fully satisfying redemption arc down the line and was basically not very interested in Luna's side of the story, so for me it felt like I got corrupt along with Leo lol and this all made it a very enjoyable experience to me. I was constantly thinking "Nah, now I'll stop walking down his NTR path here. I can always play it again" but when the moment came I just couldn't resist allowing Leo to give in, again and again. Maybe this is what the game did right. Like little games such as Witch's house, where you're deceived, this game also had an impact on me; I was seduced and between finding a scene/character sexually appealing and being seduced by a character.... There's a big gap there. It's a testament that at the very least to me, the character felt alive.
All in all, I'm slightly disappointed that we didn't get a real redemption arc(or did I mess up something?), because I could see was the true ending and the one where she takes him to paradise(didn't like that one). The true ending at least teases that something good can happen down the line.