Well... if I was to sum up my experience with this kinetic novel in one word... That word would be "Overrated".
Obviously, with this being a story with only two "pick your ending" type choices, the whole thing is all about the subjective experience. As such, one man's treasure can easily be another man's garbage.
Now, this isn't garbage for me, it was ok... but it was just ok and I can't say I really understand how it got an average rating higher than 3 stars. Part of it is because of my personal biases. At the end of the day, the "I loved her first" thing just doesn't fly as netorare for me, and it's even worse in this case, because Makoto was kind of mooning over one girl, and then only really started liking the one girl he genuinely had a chance with only AFTER she was menaced by the big bad playboy.
However, if it was just that, I could have understood. That'd just be my issue with the definitions and whatnot.
The story has a whole bunch of other issues besides that. I know that NTR of any kind is a genre where you need to turn your brain off to some degree or another, and I generally have better impressions based on how little I need to turn my brain off... This story requires a LOT of turning off of the brain. Where to even start? I can buy the usual bit with Hasegawa being an inexhaustible porn-god with an improbably large dick and literally limitless stamina... However, the story expects me to believe that by the start of it, he'd fucked near 300 girls, and that the majority of them were virgins at that. Even with VERY generous napkin math, he'd need EIGHT YEARS to go through that many women, which means that given he's probably 17, maybe 18 if he repeated a grade, he'd have started doing the whole thing since he was 9 or 10.
Really, Game? I get that the number was meant to show his stud-god nature, but it's so high as to be utterly ridiculous in the period of time he supposedly did it. On top of that, expecting me to believe that even IF that was possible, he somehow got away with it for that long without anyone finding out and rumors spreading about him is extremely absurd... especially with how careless he is. Somehow, magically, only the MC finds out about it, and none of the guys he brags too happen to be anything than turds, and somehow none of them even care that if they ever get a girl, that guy would eventually be all over her if she was even remotely hot. I could probably write an essay about how bad this whole set-up is.
At the end of the day, this, and how the events go with literally every other girl that's shown on screen, fail to make Hasegawa look like some kind of super stud. Instead, he seems more like a chosen of some lust god. The hand of the author is too blatant and obvious, and the end result is that he looks like a joke more than anything else... Library girl? Complete doormat who can't say no and instantly falls to cock. Class Prez? Had fantasies about being fucked by bad boys, also instantly falls to cock. Cheerleader? Brainless fan-girl that instantly falls to cock. Childhood Friend? Dumb as a brick and almost instantly falls to cock.
None of these girls fell because Hasegawa was that good, but because the lot of them were way too easy and dumb.
It's a pretty brutal reminder why netorare generally defaults to rape and blackmail... because without it, anyone with even two brain cells to rub together would never fall into it. It's like every woman in this story is a bimbo, or a soon-to-be bimbo with relatively minimal effort.
Then there's the MC.... It's rare to find such a dislikeable little bitch of a MC that I feel no pity for at all... but this story really did a great job of making him entirely undeserving of sympathy. He could have stopped everything from happening way before the class Prez fell. Just grab some pics of Hasegawa's idiocy, take them to the faculty, get him expelled. Sure, the sluts involved would've gotten in trouble too, but it's a small price to pay in the long run. But nope, he did nothing over and over and it was all fine and dandy until girls he was interested in started being involved, and then suddenly, it wasn't ok. He's the worst kind of hypocrite, and on top of that, even HE admitted that he was quite literally an accessory to Hasegawa's shenanigans... and that's before getting into the fact that what Hasegawa did with some of those girls definitely falls under the definition of rape and sexual harassment and likely more...
The only thing that kept this story from being a complete failure for me was the fact that, while Mizuki's slutification process was ridiculously fast, much like with the other girls, her corruption took time. It was arguably still rushed, but I suppose it works with how incredibly dumb she is. It was pretty decent overall, though it was harder to enjoy because the set-up was bad.
The art is fairly decent, but the whole thing is pretty vanilla and repetitive in terms of how things go with the girls. Only one scene with anal. One scene with toys... Nothing super impressive there. The writing for the scenes will be hit and miss. I do like how long the scenes are. I generally prefer longer scenes rather than shorter ones myself... but the story does reuse CGs a bit much during Mizuki's story, and it spends way too many lines on onomatopoeia...
Either way. Not the worst way to spend some time, but not particularly great either. I don't see what other people see in this that makes it great, even if you want to argue from the masochistic self-insert angle. I could get it if the MC was defeated because he tried and failed or was just genuinely and utterly inferior, or because he didn't know anything at all... but who the heck wants to experience defeat because they failed to act when they had so much warning it's ridiculous?