Arale Norimaki is an android built by Senbei Norimaki in Penguin Village, engineered as the perfect humanoid robot yet plagued by severe nearsightedness requiring thick, round glasses. Her appearance features purple hair, later shifting to brown in adaptations. Senbei initially declared her age as thirteen, a statement he later regretted due to her unchanging youthful look and persistently childlike demeanor. Her design evolved across the series to appear shorter and cuter, explained in-story by her possessing multiple bodies of different sizes.

Despite immense superhuman strength and high intelligence enabling feats like solving complex equations or performing amphibian surgery, Arale retains a profoundly naive personality. She lacks common sense and views the world with innocent curiosity, exhibiting a peculiar fascination with feces—often poking it with sticks, a habit antagonists like Dr. Mashirito exploit. Her interests include Japanese superheroes such as Ultraman and monster films like Godzilla, reflecting Senbei's influences. She cares deeply for family, friends, and animals, though her naivete combined with her strength frequently causes accidental destruction.

Key events begin with her creation in Senbei's lab and enrollment at Penguin Village Middle School, where she befriends Akane Kimidori and Taro Soramame. Early adventures involve rescuing a mistreated bear named Mr. Bear and later converting him into a cyborg after a hunter attacks him. She also adopted Gatchan, a winged creature hatched from a prehistoric egg, who became part of her family. Her experiences encompass time travel via Senbei's inventions, journeys to prehistoric times, and encounters with extraterrestrials like Bubibinman. Her escapades often stem from Senbei's malfunctioning creations, such as the Reality Machine warping space or the Ponpoko Morph Gun transforming objects.

In the film *Dr. Slump & Arale-chan Hoyoyo!! Tasuketa Same ni Tsurerarete...*, Arale rescues a baby shark at the beach, leading to an invitation for her and the Norimaki family to visit an underwater kingdom. During this adventure, she explores an underwater amusement park and befriends the folktale figure Urashima Tarō. Simultaneously, the antagonist Suppaman pursues her for revenge, employing gags like transforming into a Super Saiyan to halt a malfunctioning Ferris wheel. This storyline reinforces her established traits: compassion for animals, unintentional chaos during play, and obliviousness to danger. Her consistent portrayal across media cements her role as a catalyst for humor and adventure through the blend of innocence and overwhelming power.