Jam Ojisan creates Anpanman and other bread-based heroes. He appears with gray hair, fluffy eyebrows, a mustache, and lighter red cheeks and nose than Anpanman. He consistently wears a white chef's hat, shirt, pants, and apron, paired with blueish-gray shoes.

His personality radiates warmth, kindness, and a deep commitment to helping others and spreading happiness. Extensive travels in his youth filled his shelves with books and broadened his knowledge. He wields expertise in both baking and mechanics, crafting diverse dishes and building or repairing complex machines like the Anpanman Mobile.

As Anpanman's creator and caregiver, Jam Ojisan holds profound paternal affection for him, encouraging him from a young age to pursue his beliefs and strive for excellence. He extends similar mentorship and support to other creations like Melonpanna and Creampanda, fostering their growth. His bond with Batako resembles familial closeness despite no blood relation; they cohabitate and share mutual care rooted in a longstanding connection potentially dating to her infancy. He maintains cooperative ties with heroic allies such as Shokupanman and Currypanman, offering assistance when needed. His interactions with Rollpanna reveal a persistent soft spot, as he repeatedly invites her to join the bakery community despite her antagonistic tendencies stemming from an implanted "evil blue heart."

Additional lore notes include his ability to ride a motorcycle and the implication of undiscovered skills due to his inventive nature. Within the story's universe, neither he nor Batako are human, but rather fairies, as humans do not exist. Early manga depictions showed him smoking a pipe, though this trait was omitted in later adaptations.