Gengoro Island is the island on Earth, located east of Kame House and General Blue's Camp. It is where Penguin Village is located on. It is also Dragon World's version of the real world country Japan.
Gengoro Island is mostly composed by grassy plains, but some hills and small lakes can also be found here.
In the Dr. Slump special chapter "Kick the Can", Senbei Norimaki is seen running all over a map of Gengoro Island searching through the other towns of Gengoro Island for Arale and Gatchan. The various locations noted on the map other than Penguin Village are: Dumbtown, Needwife, Overthere, Mountain, Land I, Bigshore, Nowheresville, Bigtown, Poop, Station, Boonyville, Fartown, Harbor, and ABC.
Big City Island
Big City Island (ビッグシティアイランド), also known as Metropolis Island (大都会島) in the Japanese version, is an island with futuristic city full of intelligent people. It is the original home town of Charmy Yamada and Skop.
Wonder Island (ワンダーアイランド) is a strange island located a distance from Gengoro Island. It is shaped like a question mark. Many creatures mostly based off Japanese fairy tails live there. Wonder Island is the primary setting of Akira Toriyama's first manga Wonder Island. In Dr. Slump, Senbei and Arale travel to this island in order to obtain a tear from the Ogre-king Gyaska.