Jam Ojisan created and serves as the paternal figure to Anpanman, instilling life into him when a star of life fell into an anpan he baked with profound care and dedication. He wears a white chef's hat and apron, with rosy cheeks, a large nose, gray hair, fluffy eyebrows, and a mustache, visually distinct from Anpanman yet sharing similar facial traits. Residing in a bakery, he operates as both a skilled bread baker and a knowledgeable inventor, constructing mecha machines like the Anpanman Mobile and repairing mechanical characters. His youthful travels forged broad expertise, documented in his personal book collection.

He maintains a close familial bond with Anpanman, having raised him from infancy while encouraging him to pursue justice and aid others. This nurturing extends to other bread heroes: he possibly created Currypanman per early manga, acts as a father figure to Melonpanna, supports Creampanda's development, and repeatedly invites Rollpanna to join the bakery despite her dangerous blue heart compelling distance. With Batako, he shares a non-familial but deeply trusting relationship; they collaborate in the bakery and care for its inhabitants, with hints of knowing each other since her infancy. Cheese is his pet dog, though Batako interacts with the animal more closely.

Within the Anpanman universe—classified as lacking humans—Jam Ojisan and Batako are considered fairies despite human-like appearances. Early manga depicted him smoking a pipe, later omitted in adaptations. In "Mija to Mahō no Lamp," his role aligns with established traits, supporting characters through baking and mechanical skills without unique film-specific development or backstory. His consistent portrayal across media emphasizes wisdom, kindness, and unwavering support for Anpanman and allies.