Manufactured at the Matsushiba Robot Factory on September 3, 2112, Doraemon is a robotic cat designated MS-903. Originally painted yellow with functional ears, a robotic mouse accident caused their loss. This event triggered profound distress; he cried so intensely his yellow paint washed away, permanently revealing his current blue coloration and cementing his intense phobia of mice.

Sent back from the 22nd century by Sewashi Nobi, Doraemon functions as a caretaker robot tasked with improving the circumstances of Sewashi's ancestor, Nobita Nobi. His core mission is guiding Nobita toward better decisions to alter the family's impoverished future. Residing as an unofficial member of the Nobi household, this robot requires sustenance and rest.

His defining feature is a fourth-dimensional pocket storing futuristic gadgets, tools, and medicines acquired from a future department store. This pocket grants access to thousands of devices, though he frequently fumbles retrieval during emergencies, leading to comedic mishaps. While central to assisting Nobita, gadget misuse often causes unintended consequences.

Personality-wise, Doraemon exhibits deep loyalty and concern for Nobita, often panicking in crises yet persisting in support despite Nobita's recurring poor choices. He maintains familial bonds, notably with his sister Dorami, a fellow robot who occasionally aids in critical situations. His fondness for dorayaki (bean jam buns) is a core preference.

Relationships extend to neighborhood children, showing consistent patience with Shizuka Minamoto and wary avoidance of the aggressively behaved Takeshi "Gian" Goda. A subplot involves his unrequited affection for Mii-chan, a normal cat, occasionally distracting him from duties.

Doraemon's design evolved from an initial larger-bodied, kingfish-colored form with a blue tail and flesh-colored extremities to his blue-and-white appearance with a red tail and no ears. Mistaken identity as a raccoon dog due to his earless state remains a recurring frustration.