The main location of the series, in the far edge of the galaxy it's in. Dreamland and Floralia are its only large settlements, and many untouched ruins are sprinkled throughout the land. The population is low for the star's size. Some of its people are descendents of old citizens but many are fugitives and magically weak people from other stars. Others are interested in its association with anti-Dark Matter weapons (Meta Knight) and natural resources (Susie).
Popstar is home to many biomes but runs cool even in its more temperate areas. Days are slightly longer than average. Its largest oceans are southeast.
Over 2,000 years ago, Popstar was home to a larger and more advanced country, but it was devastated in a sudden attack by Nil (Popopo). Railroads were commonplace to connect Dreamland to other towns, but are now mostly abandoned. Personal carts are sometimes used for material transport and joyriding.
Dreamland is the capital city, located in flatlands north of the ocean and west of a mountain range. It was built around the Fountain of Dreams, a naturally-occurring structure on the star, and festivals are usually held around it. It has a Japanese vibe thanks to Dedede's preferences. Everyone knows eachother and new arrivals--products or people--are big news.
Kirby's house and Castle Dedede are on opposite ends of the city.
High in Popstar's atmosphere. Home to the People of the Sky, generally fairies and insect people. It's developed independently from Dreamland, so their cultures are very different, but it was also affected by Nil's attack.
Popstar was crafted by the Ancients to immobilize Dark Matter as a last resort. The star is a giant anti-Dark Matter weapon with the ability to tranquilize anyone that stays on it by emitting positive energy. An inconvenient location in a random galaxy was chosen so as to not attract others to it, but rumors got out. It's eventually successful in poisoning Nil... he was drawn to it for its immense magic, but retaliated once he realized he was too comfortable assimilating into the lives of what he considered lower lifeforms. He blew up the place and took the Warp Star captive but was sealed shortly afterward by whoever. The positive energy never left him, and it resulted in Kirby's birth centuries later.
King Dedede is the star's reincarnated spirit, called an incarnation; he was previously killed by Nil in a rage. (Which is why he always feels entitled to the star and has better resistance to DM possession.) Incarnations are spoken of as myths or rumors as it's possible they could take on something other than a human form, but they're real and among us. The Fountain of Dreams, Star Rod, and Love-Love Stick are all smaller anti-DM items. Warp Star's status is more ambiguous as she considers herself directly related to Dedede.