I don't want episodic mysteries.
The more unanswered questions and mysteries, the better.
The genre can be anything, since One Piece has a lot of mysteries even though it’s not classified as a mystery series. I want something with lots of overarching mysteries that are constantly foreshadowed, hinted at, or expanded upon—where simple mysteries become more complex as they connect to other mysteries. I also love it when new mysteries are constantly being introduced.
Example:
Re:Zero (web novel/light novel)
A song of ice and fire (novel)
Harry Potter (novel)
by ripterrariumtv