For it to be NTR it requires the girl already being in a relationship with the MC, the MC having feelings for her, or vice versa.
sigh I can answer this one without actually playing. Because Anastasia (the one in question, the blonde right?) is the fourth or fifth girl introduced to the MC, when she comes to deliver him books and give him some useless garbage which was supposed to be super meaningful or something? MC also made some comment after that. I forgot what, I thought it was just some dumb stuff, likely he was comparing her to the rest of his situation like he did with the other LIs. Which, however, does establish her as a LI, that was like 5 minutes in or less.
But if you're going to be pedantic, then allow me to do the same:
Netorare [Designed to cause jealousy by having the romantic interest involved with someone other than the MC.]
Does this cause jealousy on the players? ...check
Is she a romantic interest? ...check
Is she involved with someone other than the MC? ...check
Ergo, this is NTR. I don't care with your particular definition, otherwise we'll be throwing dictionaries at each other and it'll be a waste of time.
And if you plan in being ultra-pedantic and say it was not "designed to", it "just happened", then refer to harem.king:
Dev is saying "this is NTR" on another forum.
And as several people said, being NTR is not a crime and we don't kink-shame in F95Zone (or do we?). There's no particular reason to avoid the label, people get scared when it is a minor content/scene because this alienates a huge chunk from potential audience (those whom like, because it is lame, and those whom dislike, because it's there ─ only those whom don't mind remain). However not alienating them is arguably worse, they will have an unpleasant and unexpected surprise which might make a 180º on their opinion and caused them to start hating the game and wishing they never started it in first place. At which point sheer frustration will lead to poor reviews and worse, they might start avoiding their other games.
This being said, I can't say if that scene is currently in as they seem to have attempted a retcon, and the reason why I rated this game poorly has nothing to do with it so it's not like I care if it is or isn't in either.
PS. As for where to use the cheat codes... You can use them in the dungeon&girls game, but they're all wrong anyway.