Don't know if they will like it but I thought of, quite interesting, not really mysterious though :
https://www.mangago.me/read-manga/the_art_of_taming_a_tiger/
And I don't remember everything so I don't know if they could dislike it but I also thought of this when you mentioned mystery.
https://www.mangago.me/read-manga/criminal_interview/
Or t......
