Series that you think have great potential for NTR hentai, yet for some reason it was never really realized?
Obvious one of course is My Dress-Up Darling, which despite having perfect set ups and the perfect girl, only a couple of ero manga did the NTR decently.
Personally pick is Dangers in my Heart, which for the exception of that one untranslated one that does an alternate timeline 5 years later, has like no NTR works of note.
Gridman has a couple of gems, but not enough despite a perfect girl for it and even an episode that pretty much was an NTR set up.
Dandadan has like basically no porn manga expect that gangbang one, despite a great girl and plenty of bait in the actual manga.
Blue Box has recently introduced a character that might create some nice set ups at least, let’s hope it delivers something.