Oz Vessalius spends his 15th birthday running away from his maids with his younger sister, Ada, and servant, Gilbert. They hide at Oz's secret spot where he accidentally falls through the ground leading to a hidden grove containing a single grave with a pocket watch attached to it. When Oz grabs the pocket watch from the tomb, he sees a vision of himself being strangled by a girl before being brought back to reality by Gilbert. While he prepares for his coming-of-age ceremony, strange figures gather and prepare to carry out their scheme.