The ruler of the evil Phantom Empire, Queen Mirage, begins her invasion on Earth using an army of Choiarks and powerful monsters called Saiarks. All across the world, Pretty Cures are dispatched to fight against the Phantom Empire threat. Shirayuki Hime, a princess from the Blue Sky Kingdom, which was taken over by the Phantom Empire, joins the fight as a Pretty Cure named Cure Princess, but always finds herself running away scared.

Given a Crystal of Love by the Spirit of Earth, Blue, and told to seek out a partner to fight alongside her, Hime goes to the city of Pikarigaoka and randomly throws the crystal into the air, deciding to partner up with whoever it lands upon. This person turns out to be Aino Megumi, a kind-hearted girl always looking to help others, who is recruited by Hime to fight by her side as Cure Lovely. Using the power of the PreCards and their changing forms, alongside Cure Honey and Cure Fortune, they form the HappinessCharge Pretty Cure team as they are given the task to collect all of the PreCards and defend the Earth against the Phantom Empire.

Source: Wikipedia

AniDB | ANN | MAL | TVDB | Wiki (en)

Same setting: Futari wa Precure
Side story: Eiga Happiness Charge Precure! Ningyou no Kuni no Ballerina