Responses

주인 (ju-in) is probably what they called MC. 주인 can both mean "master, landlord, host". but ML mistook the meaning
the friends should've called MC 집주인 (jib ju-in) because it has a clearer meaning which is "house owner" instead of just calling him 주인님 that could translate to a lot of other meanings haha
But like now I don’t remember why his friends called him “master” (⊙…⊙ )