Naku Tsukishiro had everything he ever wanted. It's easy for him to live like that when you're born a crowned prince. Having a lot of friends, he's felt like something is missing, like it was missing all his life. One day his life got turned upside down when his father tells him something that he needed to know. Now he had to go to the Earth dimension in search of his brother before his coronation on his birthday. If he doesn't return with his brother before the deadline, the crown would fall into the forces of darkness threatening the safety of both of the dimensions. Four servants, one Prince, one mission. It was now the time for Naku to head on to his new school and face all kinds of danger. Will they make it in time to avoid chaos, or will the Dark Ruler destroy both of our dimensions? It would take all of his power to make the right choices and get back before the deadline.