Senbei Norimaki is a 28-year-old eccentric inventor residing in Penguin Village, known for his lecherous tendencies offset by genuine scientific brilliance. He crafted the robot girl Arale Norimaki, initially envisioned as the world's most perfect little girl robot, though she required corrective eyeglasses shortly after activation. His inventions frequently trigger unintended consequences due to Arale's naivety and superhuman strength. He alternates between introducing Arale to other villagers as his younger sister or daughter.

Professionally, Senbei imagines himself as a handsomer, taller figure when attempting seriousness, a recurring visual gag. His romantic pursuits focus on Midori Yamabuki, Arale's teacher. After prolonged misunderstandings, he proposed to Midori, mistakenly believing she was out of earshot; she immediately accepted, leading to their marriage and her becoming Midori Norimaki. Despite Senbei's initial confusion about human reproduction, the couple later had a biological son named Turbo.

His scientific endeavors extend beyond Arale. He brought an egg back from a time travel trip to the Stone Age; it hatched into Gatchan (Gajira Norimaki), a green-haired, winged creature with metal-eating tendencies and ray-shooting capabilities. Gatchan eventually splits into two entities after metamorphosis. Senbei's actions frequently initiate chaotic events in Penguin Village, often resolved through Arale's intervention or his own resourcefulness.

Across various media, including crossovers, he maintains his role as an inventor, notably appearing briefly in the *Dragon Ball* series to repair Son Goku's Dragon Radar. His core traits—scientific ambition, comedic romantic failings, and sporadic responsibility—remain consistent. He uses the distinctive greeting "N'cha," which Arale adopts.