The noble William possesses a rare kind of intelligence. The school he attends and his family background both draw much attention. However, one day, his family loses money after his uncle's business fails. Worrying about how this would affect his school's reputation, he returns home to help the family butler search for things to sell. What they found was an underground room that had been used by William's ancestors. The room contains a magical seal, with which William unintentionally summons a demon. The demon, Dantalion tells William that he has the ability to choose the king of the demon world! Naturally, the candidates for king will come after William… who will become king in the end?!

In the continent of Polyphonica, spirits materialize in the world, surviving on the music that is played by humans, and live together with them. While the spirits don't appear often, some spirits have enough power to materialize in human or animal forms and live together with humans. Dantists, who play special music called "Commandia," are widely respected in this world. They are usually in contract with powerful spirits. The story of Shinkyoku Sōkai Polyphonica Eternal White revolves around the new Dantist, Snow Drop, a maid who cherishes her Ojou-sama more than anything, and her Contracted Spirit, Blanca, who is also known as the famous Contra Bass, Eternal White.

From Storm in Heaven: Touko Hanamori is the young successor to the Hanamori family's line of priestesses. What she longs for, however, is to have a normal life–to have a boyfriend, go on dates, and live like a normal girl would. A new job introduces her to a handsome young man, but will this be the start of a blooming romance…or is there something she doesn't yet realize?

A timid boy named Zao Ci***, which was accepted by Mateliya, a Demon as her "number 2". He was always called an idiot by Mateliya. He is so weak that he could not even pull the trigger of his gun. But, who actually knows that he had a special power within him, which only Mateliya can control. This begins the adventure of the contract of the boy and his master to save others. ***Later on Zao Ci's name is corrected and changed to Koji

Luca Athrason has been sentenced with 500 years of imprisonment – such is the price to pay for his sins. The only way for him to shorten his sentence is to accomplish his missions as the Church’s vanguard or as some might call it… The Church’s Dog!