Oz Bezarius is a young noble about to experience his coming-of-age ceremony, which he is none too happy about. He could care less about the proceedings, but decides to do them anyways. On the upside, he is able to visit his uncle Oscar's mansion, which has a lot of different places to explore, which satisfies the young master's curiosity. He travels around the mansion with his little sister, and friend and servant Gilbert, causing mischief for the house's staff.
Oz and his "gang" are finally caught by his uncle Oscar, who agrees to let him play a little longer, provided that he does not mess up the ceremony in any way. Oscar threatens to summon a Chain of the Abyss onto him. Undeterred by the threat, Oz, his sister, and Gilbert proceed out the window with a suitcase Oscar had provided them.
Oz shows a suit that was inside the case to Gilbert, who comments that it's to small for Oz. Oz lets him know that it's small because it's intended for Gilbert, not himself, much to Gilbert's discomfort. He feels that he is much too low on the social rank to have a spot in the coming-of-age ceremony. Oz laughs it off and starts to walk away, until the ground collapses beneath him.
In the pit, Gilbert and Oz fund a grave marker with a pocket watch on it. Oz, feeling the watch call to him, picks it up. Next thing he knows, he's in a room filled with dolls that talk to him. Things get even stranger when a girl appears, expressing happiness. Then, suddenly, she tries to kill Oz, who snaps back to reality just as the killing blow was struck. He and Gilbert leave the pit, Oz clearly disturbed.
Before the ceremony, Gilbert, who is contemplating whether or not to go, is attacked by a mysterious person, who it appears possesses his body. Oz listens to the pocket watch, and we see another mysterious person wondering if she's being called.