I got the ruleset for One Night Werewolf:Monsters and it mentions that it can be played with 3-7 players. However, I don't think it is clear if the Master is also a player or just narrates the game and does not actually play?
All play. You don't need a master: the players can all call the time/sequence (with their heads down and eyes closed) as needed. If you have a spare "player" who wants to moderate, that's fine, too, of course.