I have a question, does Miki really love Producer or is it just fanservice for the game.
Yes, all the idols are meant to show attraction to the producer to some extent in the games, and it is reflected in the anime. There is an alternative version of Miki known as Awakened Miki that is shown to be very romantic with the producer. Awakened Miki is the opposite of Hoshii Miki however, in that she is a very hard worker instead of being lazy.