From MangaHelpers:

On a beautiful island, a little girl named Takeru meets the mysterious brothers Tesla and Marin who have the ability to fly. These brothers have been called many names by the locals of the island, including "The White Witch," monsters, and demons, but more scientifically, they have been named "Utility." To uncover the mysteries of their powers, the older brother Tesla has employed the help of the local researcher who happens to be Takeru's mother. As Takeru and Marin become closer friends, the uncovering of the mysteries of the "Utility" create an epic story of romance and destruction on this once peaceful island. [DrCoke]