Princess Exonia grew up in exoplanet.Her father is the king Exon and her mother died,because she was a human and humans can't life in exoplanet.King Exon choose 12 guaridans called EXO,who swear to protect her with their own lifes.There is just one Problem:Exonia hate to beeing a princess and want to life like normal humans in the humans world called the earth.For she is forbidden to go on the planet wolrd.But one night she sneaks out of the castle to life on the earth.Exon gets really mad.He commands the Guardians to go on the earth to find an bring her back.The guardians do as told.But in the humans world they are a way too handsome and a company called SMtown want make them to K-Pop Idols.But what will happen to princess Exonia?