Oz is the heir to the Vessalius house, one of the Four Great Dukedoms given excessive power by the country's royalty. He lives a luxurious life alongside his younger sister Ada and valet and best friend Gilbert. This extravagant lifestyle is only diminished by the constant absence of Oz's father Xai, who decided Oz and Ada should be raised by their uncle Oscar when they were still babies. When Oz goes to his Coming-of-Age Ceremony, he meets Sharon Rainsworth and her ominous servant Xerxes Break. Everything appears normal until the Coming-of-Age Ceremony rituals are completed and the giant clock that hasn't worked in a century moves. Suddenly, a group of people in red cloaks known as the Baskervilles proceed to reveal themselves. The Baskervilles say he must be dragged into a supernatural prison called Abyss where monsters called Chains live, a place previously believed to have only existed in fairy tales. The Baskervilles then force Oz into the Abyss, claiming his existence to be a sin, although Oz is clueless as to the true meaning behind these words and the desire to acquire it becomes a driving force for the rest of the series.