The story follows Oz Vessalius, the 15-year old heir to the house of Vessalius. During his coming-of-age ceremony is set upon by strangers who condemn him for the sin of being alive and banish him into the depths of Abyss, an otherworldly dimension.
Episode 1
Innocent Calm 罪なき平穏
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.