Kamui is the mastermind.It'll be funny is he's the mastermind, considering in Chapter 1 Asami was the one who died, not him.
There are multiple traitors.There are multiple traitors working under Monokuma, not just Kakuma who is pretending to be the traitor. Monokuma didn't only reach Kakuma, but other people.
Minori is the mastermind.Minori and Monokuma talk to each other a lot. Though it isn't known how much Monokuma talks to the others, Minori and Monokuma's interactions are... suspicious, to say the least. Monokuma is acting as if he expects Minori to do something. Monokuma acts as if Minori was a friend of his- as if Minori was working with him. It would make sense if Minori was the mastermind considering the dreams he's been having. I think him being the mastermind is involuntarily and/or that he's unaware that he's one.
This is another season of Danganronpa.I don't know, just throwing it out there.