Monotone, to not be confused with the developer MonotoneDoc, is a mysterious and apprehensive character, being MonotoneDoc's Among Us Sona, appearing in Identity Crisis, and a joke song called Plague Energy. For unknown reasons, his song is only unlocked upon completing Story Mode. Defeating him will cause Black to appear and challenge the player to a rematch, leading to his takeover of the mod and Finale. Monotone is a Shapeshifter, a subspecies of an average Impostor. This gives him the ability to appear as perfect clones of Boyfriend, Red, Green, and Black. When not disguised, Monotone is a black bean-shaped astronaut (Not to be confused with Black Impostor.) He wears a sharp tuxedo with a red tie and a small black top hat. He wears a traditional plague doctor mask, completely covering his visor. Similarly to Black, he has a constant yellow glow emanating from his eyes. His microphone is very rectangular and attached to a stand. Monotone in Identity Crisis and MonotoneDoc in Monotone Attack are the same person, not the same character.

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