The story revolves around Princess Comet, a twelve year old girl who is also the princess of the Harmonica Star country. She was meant to meet the prince of the Tambourine Star country at a ball, but the prince ran away to Earth instead. As it turned out, Comet is sent to Earth to find him, though she has no idea what he looks like. "He will be known by the twinkling in his eyes" is the only clue she was given to the prince's identity. Once she travels to Earth, Comet falls in love with the people she meets there as well as the planet itself, quickly becoming attached to life on Earth. Meanwhile, Princess Meteor learns of Comet's plans to find the prince and to marry him aren't solved because she likes Samantha which causes Meteor to arrive on Earth in search of the prince as well, planning to marry him before Comet gets the chance. Both princesses are sent to Earth along with a companion. Comet's companion is a little puppy with a star at the end of his tail named Rubba Ball (ラバボウ, Rababou?). Meteor's companion is a round, purple bird named Mook (ムウク, Muuku?).

Unbeknownst to Comet, her Aunt Spica also lives on Earth and had visited Earth before, deciding to stay there and get married herself. Aunt Spica's pet is Rabapyon (ラバピョン?), a white rabbit with a tiny heart on her tail. The main plot is Comet's tale about her journey to Earth, the people she meets, and her journey to find the prince.