After the major events of Pokémon FireRed and LeafGreen, two protagonists, Aster and Star, arrive in the Kanto region, revealing mysterious magical powers. Some people accept them, others do not. Rumors spread that they come from a strange land called the Ceastil Region, which will be explored in Pokémon Delectable.
Before the stellar meteors fall upon Kanto, Aster and Star spend time shopping in Celadon City. Around this time, Nono Hana appears on the news announcing that HUGtto! Pretty Cure will be ending and that Star Twinkle Pretty Cure will soon begin, introducing Hoshina Hikaru as the new protagonist. Star instantly adores her and calls her a “stellar idol.”
Excited by the announcement, Aster and Star buy merchandise related to the new magical girl series. Among the items they bring home is a plush of a mysterious new Pokémon described as “cuddly and sweet.” Star names it Purikuheart, the mascot of the game. They place it beside them as they fall asleep, leaving behind the Twinkle Book on a cabinet near a Star Twinkle Pretty Cure poster.
Soon after, stellar meteors begin falling from the sky, reshaping the entire Kanto region. New environments, locations, and routes emerge. One meteor nearly strikes Pallet Town, but a Pokemon called Fuuwacorn appears and explains that it came from the Twinkle Book.
The next day, a mysterious new professor named Professor Sakura arrives and explains that the Twinkle Book is a powerful artifact. It had sealed Fuuwacorn inside for many years and was previously locked away in the Pokémon Mansion on Cinnabar Island.
Before their adventure truly begins, Aster and Star wake up filled with excitement. They use their Twinkle Rods, when suddenly a new rival named Rhea appears, loud and energetic. Aster comments that the series Star Twinkle Pretty Cure premieres on February 3rd, 2019, placing the events of Pokémon Stellar between Generations 7 and 8.
And so, Aster and Star, the two magical protagonists, begin a grand new adventure across a transformed Kanto region.