He is part of a group called the Monokuma Cubs along with his siblings Monotaro, Monosuke, Monokid, and Monofunny. While all the siblings are robots, he is the most robotic in appearance. He is the most quiet member of the group.
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Spoilers start here.
Monodam deliberately kills himself during Korekiyo Shinguji's execution by running into the fire in the hopes of making it burn faster in Chapter 3.
Spoilers end here.
Monodam's appearance is similar to that of his father, Monokuma, but the part that is black on Monokuma is olive green. Likewise, his right eye is gray with a red pupil while his left eye is white. He also has light gray cheeks, meant to represent blushing, and a yellow pacifier in his mouth to represent the fact that he is a child.
While all the siblings are robots, Monodam is more robotic in appearance, his limbs being made of gray, bendable metal. He also speaks in a stereotypical robotic way.
When he gets nervous, his ears pop up, releasing steam. Like a rocket, he is also capable of flying forward very fast, leaving behind a trail of bright light.
Monodam is a child-like robot. Unlike his overly talkative siblings, he is quiet. For the most part, he doesn't speak to his fellow siblings. When he does talk, he speaks in a typical monotone robotic manner. This along with the fact that he appears rather emotionless causes him to come across rather creepy at times, much more so than his siblings.
He is constantly bullied by Monokid, both verbally and physically, possibly because of his different looks. This is the reason why Monodam has closed his heart long ago.
Monokuma is the self-proclaimed father of Monodam, Monotaro, Monokid, Monosuke and Monofunny. He calls them his "adorable children", but apparently he also has a tendency to punch them if they annoy him. Considering himself the headmaster, Monokuma seems annoyed if his children try to steal the show.
Monokid loves to bully Monodam, both verbally and physically, even though they should be comrades. Monokid says Monodam has "an ugly and cheap-looking body", implying that he may dislike him because of his different looks. This is the reason why Monodam has closed his heart long ago.
Like Gundham Tanaka, his name is a reference to the Gundam mecha anime series. His much stronger resemblance to a stereotypical robot compared to the other Monokuma units can also be seen as further referencing it.