Man... reading through this thread was more of a trip than the actual kinetic novel. Seriously hilarious tbh...
Anyway... For me, this was a decent slutification story for the most part, with only minimal corruption content. The girl going from innocent virgin to sex addict was pretty well done, but I can't really call her all that corrupt since at the end of the day, she still had standards and still tried to find a guy that was more than a sex monster. If she'd actually been corrupted, she'd have stuck with the somehow good at sex fat kid and she'd have let him train her asshole until all of her body was his exclusive to use onahole.
Instead, she basically decided to repeat what she did with the kid she tutored, only with the childhood friend which she knew she could trust.
What's pretty funny is that when she was even semi-seriously with any one guy, she never did with any other guy until she left them or they were forced out of the equation somehow. By the time she decided to train up her friend, she'd already decided that she was cut things off with the last guy in the list, she just waited until she did it in the most brutal way possible... but it's not like they were actually going out anyway.
In any case, the story's barely there, the characters are barely developed, the MC is an unlikeable moron... The main strong point of this thing is the art. This is definitely one of those artists that genuinely makes the girl look soft, and just curvy, with the skindentations in places, and the way fingers actually sink into her tits and ass when groping is shown.
Not a terrible time-waster, but for me at least, this doesn't register as NTR. The whole "I loved her first" thing is just completely delusional bullshit... But hey, good on Mai for finding her own happy ending, maybe. It's a fictional story, whatever happens after it ends is completely up to the reader if no sequel exists... and given how much time has passed since this one was finished, odds are high that there will never be one. I personally think that her fuck-crazed friend will be able to keep up with her and that they'll live happily ever after and all that jazz.