Kuma-san is a sentient stuffed bear of unknown origin, recognized by his large blue fabric body and typically expressionless face. He carries a drum and drumstick, performing for children in the town plaza alongside a supportive clown companion. When angered, Kuma-san transforms into "Super Kuma-san," donning a neckerchief and adopting an unconventional protective role against local criminals. His methods include lunging at threats or banging his drum. However, his effectiveness is inconsistent due to a childlike naivety and easy distraction by simple pleasures like ice cream.

A core trait is his emotional vulnerability. Glimpsing his own "scary face" during heroic acts triggers trauma, plunging him into depressive states where he flails helplessly. Brief flashbacks hint at an unspecified tragic past, fueling his motivation to protect others. His existence is complicated by a rivalry with another sentient toy: a vengeful living doll clad in a tutu, possessing murderous intent. This doll's own tragic backstory, revealed through flashbacks, creates a contrast in their motivations, with their conflict rooted in their shared existence as animate objects.

Kuma-san displays inherent kindness and a strong attachment to children, often prioritizing their safety amid chaotic events like bank robberies or vandalism. His relationship with the clown, while supportive, remains underdeveloped, with the clown primarily serving as a narrative anchor during their performances. Kuma-san's design allows only limited facial mobility, yet subtle shifts in his mouth shape convey emotions ranging from determination to distress. A darker aspect emerges in his "berserk mode," showcasing uncontrolled rage during confrontations.