Senbei Norimaki, universally known by his nickname Dr. Slump, is the eccentric genius inventor residing in the quirky Penguin Village. He is a portly man with bushy black hair and a mustache, often seen wearing a white lab coat or a cap bearing the word "Slump". Orphaned at a young age, he attended Penguin Village Middle School where he developed his first crush on a teacher, a pattern that would continue into adulthood. A bizarre incident from his youth, in which a dog called him stupid, instilled a permanent aversion to canines. His name is a playful pun on "senbei," a type of Japanese rice cracker, and "norimaki," meaning "wrapped in seaweed".

Dr. Slump possesses a brilliant scientific mind, yet this genius is constantly at odds with a profound lack of common sense and a highly eccentric, lecherous personality. His primary motivations are often driven by his whims, which frequently include a desire to see attractive women, particularly Arale's teacher, Midori Yamabuki. This obsession with Midori is a major story driver, leading to a long series of awkward romantic misadventures that eventually culminate in their accidental marriage after he inadvertently proposes while she is using a restroom. Their union results in the birth of a biological son, Turbo Norimaki.

Despite his bumbling and selfish nature, Senbei's central role is as the creator and paternal guardian of the android Arale Norimaki. Although the series is named after him, the focus shifted to Arale as the main protagonist early on, a change made at the request of his editor. Senbei introduces Arale to the world inconsistently, sometimes as his younger sister and other times as his daughter. His family grows to include Gatchan, a small, winged, metal-eating creature hatched from an egg he brought back from a prehistoric time-travel trip. A prominent running gag involves Senbei temporarily transforming into a tall, handsome, and rugged version of himself whenever he feels confident or attempts to look serious, a state that lasts for only three minutes.

His inventions are the primary outlet for his genius and the source of most of the series' chaos. They range from brilliant to absurdly impractical, including the See-Thru Glasses for viewing through clothing, the Big-Small Gun for resizing objects, the Time Slipper for time travel, and the Reality Machine, which can manifest objects from pictures. His most significant creation is Arale herself, whom he designed as a perfect humanoid robot, though her final flaw is severe nearsightedness, requiring her to wear large glasses. His rivalry with the villainous Dr. Mashirito, a parody of his real-life editor, adds a layer of meta-humor to his story. Senbei's character also appears in the Dragon Ball universe, where he interacts with Son Goku, attempting and failing to repair the Dragon Radar, only for his son Turbo to secretly fix it. Throughout his many misadventures, despite his lecherous and irresponsible tendencies, Senbei remains a devoted father figure and his unwavering passion for invention solidifies his legacy as the heart of Penguin Village.