Mob Characters are fan-created characters submitted by viewers of Monster Musume: Everyday Life with Monster Girls and inserted into the manga by Okayado. Serving as background characters, Mob Characters were a ploy by Okayado to enable fans to become involved in the making of the manga series. By submitting a form which involved a drawn sketch of their character, their name, age and their favorite monster-girl species, fans could have their character be drawn into the manga's background and crowd scenes typically paired off with a member of their favorite monster-girl species.
- There is a notable difference between the magazine and the tankobon versions of Chapter 49 and Chapter 50 due to the chapter being incomplete, and as an apology, Okayado asked fans to choose to be one of the 20 male background characters that appear in the chapter (that's why they all had numbers). He added them in the final release of the volume, along with other fixes. While the original call was for twenty human male "Mob Characters", Okayado tried to fit as many entry characters as possible into the chapter. As a result many crowd and location scenes in the chapters were altered from their appearance in the original magazine release to include these characters.
- Chapter 64 is the first instance of female Mob Characters being introduced to the manga.