Key point here is the intentionally vague "someone" at the door. Also you forgot the witch is real. Remember the witch is targeting vulnerable men who live alone. It's far more reasonable to assume that the someone at the door is the witch looking to set them up. All the victims took the drug, the witch distributed the drug, all the victims met "someone" at the door. Just because we only deal with the witch at her stall doesn't mean she didn't personally visit them. If we assume that the witch is visiting them in person and that is the someone people see, then it's also reasonable to assume that Leanna IS the witch either in disguise or warped by their perception. And other instances where the characters mention the MC "with another person" like miss peeping tom can't be relied upon because those are all witnessed through the MC's drugged state. That said, I realized one plothole while I was thinking about all this that I can't explain in all of that could destroy my theory here. Something you haven't mentioned yet. Buuuuuut I'm not telling, I want to see if you figure it out yourself.
Somewhere along the line of writing this I lost my enthusiasm for talking about this game. Though the discussion was interesting this is the end for me so sorry if I don't continue after this fellow theorist. it's probably the depression kicking in because it's 2am and I haven't slept well in months.
