Jam Ojisan serves as Anpanman's creator and a central paternal figure. His origins trace back to baking the anpan that became Anpanman's head when a shooting star imbued it with life, forging their intrinsic bond. He operates as a baker from a distinctive house-shaped bakery, recognized for extensive culinary expertise and profound knowledge across diverse fields. His appearance features a white chef's uniform, fluffy eyebrows, a mustache, and lighter red cheek and nose coloration compared to Anpanman, reflecting his advanced age.

Beyond baking, he demonstrates exceptional mechanical aptitude, designing and constructing specialized mecha like the Anpanman Mobile to aid the heroes. He maintains the heroes' functionality by baking replacement heads when they sustain damage, especially for Anpanman, whose strength wanes if his head becomes wet, dirty, or partially eaten to feed the hungry. He also repairs their torn capes, essential for flight. His vast knowledge base stems from extensive travels during his youth, evidenced by his large book collection.

His foundational relationships reflect his paternal nature. He exhibits deep care for Anpanman, whom he raised from infancy, encouraging him to pursue justice and aid others. He extends this nurturing role to other bread heroes: Melonpanna regards him as a father figure, and he actively supports Creampanda's development as an adoptive guardian. While not biologically related to his assistant Batako, they share a familial bond through long-term cohabitation and collaboration in bakery operations and cape maintenance. His connection to Currypanman remains ambiguous, with early manga indicating possible creation by Jam Ojisan, though later anime themes suggest uncertain origins. His interactions with Rollpanna are cautious due to her dual-hearted nature, yet he periodically invites her to join the bakery household despite the risks.

A canonical Q&A clarifies that the Anpanman world lacks conventional humans, classifying Jam Ojisan and Batako as "fairies" despite their human-like forms. He possesses diverse undocumented skills, including motorcycle proficiency, with potential for unforeseen abilities. While early literary depictions showed him smoking a pipe, this characteristic was omitted from the anime adaptation. He remains unaware of Anpanman's exact birthday due to the absence of calendars, though he retains personal knowledge of the event. The franchise holds a Guinness World Record for its vast character roster, contextualizing Jam Ojisan's role within this expansive universe.