Long ago people settled down on the moon and established a kingdom there, the Sphere Kingdom. However, relations to the earth cooled down and were finally broken off since a war was fought hundreds of years ago. There isn't any business between the two races and traveling isn't allowed. The only link between them is to be found in the Mitsurugasaki Central Port City. However, one day the princess of the moon kingdom, Feena Fam Earthlight, is sent on a "homestay" to the earth. She gets to stay at Asagiri Tatsuya's house. And this is where her journey begins.