Monotaro is the leader figure of the Monokubs. As a leader, he tries to unite the group members' discordant voices into one. However, being a scatterbrain, he gets sidetracked a lot and often struggles to keep his rambunctious siblings focused on the task at hand. He is also mentioned to have a clumsy side, giving him a childlike charm, and he often acts the most child-like and "pure" out of the siblings. Despite not being a very competent leader nor the smartest, his siblings consider him a reliable figure. Monotaro is relatively mild-mannered and less openly hostile towards the students, though like all the Kubs he calls the students "you bastards" seemingly as an attempt to imitate his father. Nevertheless, he is evil, just like all the siblings. He occasionally bullies his siblings and fights with them, just like all the Monokubs do. Monotaro has always been a bit forgetful, and often forgets events or people.

Monotaro has a pretty distinct voice, that is around the medium to medium high range for a male. It sounds fairly nasally. He is one of the more sensitive of the Monokubs, and therefore often cries or gets upset.