This is surprisingly well made. :3

Base +6

Game is tagged as NTR on dlsite, but the girl is MC's little sister, so not really sure how actually applicable the tag is.

Base +7, 555666777 -7, Chapell -6, Eglaic -6, jzntr -4, EroticWaffle -7, wenx° -21

u know why people downvote u?
Because u do not really understand what NTR(netorare) is.
It's not cuck.It doesn't care if she love the protagonist.
Also doesn't care what relationships they are.Boy and girl friend,brother and sister,husband and wife,mom and son.
whatever relationships in the Japanese ero mangas and games are OK
Just protagonist know who he loves get fucked by others,he feel uncomfortable
or he don't know for now like he works at his company or he studies hard but if he knows the truth he will be uncomfortable and heartbroken.
That's NTR

In my opinion,some mangas and games tell a shota or a guy fucks a married lady and in the whole manga her husband do not even show up
Not to mention his mental description.
That's not NTR.
what is important for NTR is perspective or view angle.
It must have mental depiction of the protagonist,even a little is enough.

Base +6, wenx° +21, juevy -10