Based on my feelings I´d narrow down the Reaper / Vampire Cult candidates to SK, Blue, Pero, Zolo and Light.
Not so unlikely for cult to have an investigation ability and SK and Ekko were getting along a bit too well yesterday.
Pero was one of the people to tried making me look like a vampire myself, alongside Baki who flipped mafia scum.
In the beginning Ekko suspected Light a lot but suddenly he completely stopped mentioning him, so maybe Ekko and husbando sis Nana were right about Light all along but Ekko got culted by Light and so he stopped accusing him of course.
For the other two I don´t have really strong arguments, it´s based on my intuition, Blue is quite capable of staying under the radar despite making a lot of posts, I have that strange feeling he could also probably be Mephisto.
Zolo is just... there lol and is only talking about indie hunting, nothing else. Out of those five he´s the one I´d take out last, although I can imagine him being a reaper somehow.