Can you suggest me games like this please?
which includes the mysterious NTR
Well, the most similar is Henteria Chronicles but if you know this game you probably already know HC.
NTR online is good, its NTR is not as mysterious as this one but that doesn't mean it's not a good game, also if you like 3D CG this is your game.
There is one based on Konosuba (can't remember the name, sorry) that is very similar to NTR Online.
Agunosutosu games are good in story, but the sprite quality leaves much to be desired.
NTRPG is already a classic and even though it's old it's still better than several new games.
Boy Hero Ken Haunted House Investigation maybe can be part of that mysterious NTR you are looking for.
But if you are looking for a game that is not slow in terms of corruption and where the girls are whores almost from the start then I recommend Whispers of the Dark Elf and My Girlfriend Advanced to the Dancer class and she buffs everybody.