The Secret of Arale's Birth (アラレ出生のひみつ Arare shussei no himitsu) is the 86th episode of Dr. Slump Arale-chan.
Synopsis[]
Senbei's grandfather and his grandson, Ryota, come to Penguin Village. When grandpa hears Arale is Senbei's younger sister, he starts wondering because Senbei's parents passed away more than 20 years ago but Arale is still only 13 years old...