Midori Norimaki, originally Midori Yamabuki, teaches at Penguin Village Junior High School. She first meets Senbei Norimaki when he enrolls Arale as his sister, immediately catching his romantic attention. As a child, she became lost at an amusement park and was accidentally transported to Planet Takeya-Saodake. The planet's childless king and queen adopted her there. Years later, they returned her to her Earth parents, though she pledged to become their successor if required.

Midori sports distinctive curly blonde hair, depicted as brown in the 1997 anime adaptation. Her resemblance to another character, Akane, enables comedic impersonation scenarios. She favors casual dresses, though her specific attire varies across adaptations.

Kindhearted and friendly toward students, Midori occasionally displays anger and grows increasingly scatterbrained after marriage. Senbei frequently targets her with schemes like elaborate underwear-peeking attempts or hidden bath cameras, though she often remains oblivious. Their relationship shifts when Senbei mumbles a marriage proposal near the bathroom; she overhears and instantly accepts, leading to their wedding.

After marrying, Midori moves in with Senbei, acting as surrogate mother to Arale. She later births their son Turbo, who gains psychic powers following an alien spacecraft encounter. In the sequel manga *The Brief Return of Dr. Slump*, she has a second child named Nitro. Her family routines include grocery shopping with Turbo, where she encounters Arale decades later without visible aging.

In *Dr. Slump & Arale-chan Hoyoyo!! Tasuketa Same ni Tsurerarete...*, Midori joins the Norimaki family's underwater kingdom adventure after Arale rescues a baby shark.

Midori appears in *Dragon Ball* crossovers. During Goku’s Penguin Village visit, she bakes him cookies and witnesses Arale defeat General Blue. Goku initially confuses her for Senbei due to her appearance.