We first meet Arale when she's just a head in the lab of Senbei Norimaki's lab, but even without a body she proves to be a naughty, still innocent girl. Her body uses a fuel called Robovita-A, which she sucks from a baby bottle. If she run out of the wonderful beverage, she automatically switches off.
Her best friends (and adoptive sisters) are Gatchan and Gatchan, two winged little girls who spend all day playing with Arale, and eat everything that comes close enough to their mouths.
Although she is a robot, only Senbei and the Gatchans knows it in all Penguin Village, despite Arale regularly playing with her own head, separating it from her body and throwing it into the air.
There is clone robot of Arale, called Obotchaman (first known as Caramel-Man #4) who was created by Dr. Mashirito, Dr. Norimaki's archenemy, as a part of his plans to kill Arale and rule the world. Eventually Caramel-Man #4 falls in love for Arale and they become friends, which leads him to change his name to Obotchaman and ruin Mashirito's plan again.
Arale has a cameo appearance in Dragon Ball, where she helps Goku fighting against General Blue, a powerful foe from Red Ribbon Army who pretends to steal the dragon balls for his master, Commander Red.