Title: パンドラハーツ / Pandora Hātsu
English Title: Pandora Hearts
Genre: Psychological Thriller, Gaslamp Fantasy, Drama, Mystery
Episodes: 25
Summary: 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.
Trapped in the Abyss, Oz finds out he can make contracts with Chains by drinking their blood. He does so with a Chain named Alice, infamously known as the Bloody Black Rabbit (or B-Rabbit for short), in order to escape the prison. By the time they escape from the Abyss, ten years have already passed. He is taken under the care of Sharon and Break, who he discovers are members of a Chain-research organization called Pandora that was established a century ago after a disaster known as the Tragedy of Sablier (in which the entire city of Sablier fell into the Abyss) by the Four Great Dukedoms. Wanting to understand why his existence is supposedly a sin, Oz helps Sharon and Break in their investigation in regards to the Intention of the Abyss, the ruler of the Abyss. They have the help of Alice and adult Gilbert, who has now been adopted into the Nightray dukedom and made a contract with the family's chain, Raven. As they investigate, they learn that Alice, Gilbert, and Gilbert's odd younger brother Vincent were involved with the Tragedy of Sablier. Additionally, they come into contact with the soul of Jack Vessalius, the legendary hero of the Tragedy of Sablier who prevented the entire world from being dragged into the Abyss after such a thing happened to Sablier. Jack was also the one who established Pandora. In the current time, he lay dormant in Oz's body. Jack reveals that the one behind the Tragedy of Sablier was Glen Baskerville, the head of Baskervilles and his best friend.
Following a meeting with Duke Rufus Barma, Break reveals he became an illegal contractor thirty years prior and has met the Intention of the Abyss, who is in fact Alice's twin sister. Duke Barma reveals that, according to his ancestor Arthur Barma's memoirs, Jack has sealed Glen's soul by placing it within his own mutilated body, split into five sealing stones. Following the destruction of two of the five sealing stones, Oz and Duke Barma trick foreign noble Isla Yura into conducting a second Coming-of-Age Ceremony for the former in his mansion, wherein one of the sealing stones is located. However, in the middle of the party, Yura and his sect start killing the guests in an attempt to reenact the Tragedy of Sablier. Although Oz and his friends manage to stop Yura's cult from succeeding in their efforts, the sealing stone is destroyed by the Baskervilles and Gilbert's adoptive younger brother, Elliot Nightray, is killed. This leads to Elliot's valet Leo being taken away by Vincent, who reveals that Leo holds Glen Baskerville's soul within him, and thus is the next successor of Baskerville clan. Blaming himself for Elliot's death, Leo accepts his role as Glen Baskerville in order to destroy the Intention of the Abyss.
The Baskervilles and Pandora clash as Leo attacks the latter. Upon destroying the fourth sealing stone, the fourth seal is revealed to contain Glen's head rather than Jack's. Duke Barma then declares he has deciphered an entire code within Arthur Barma's memoirs, which, once decoded, reveal Jack is actually the one who caused the Tragedy of Sablier. Oz then witnesses Jack's memories. It is revealed from such that Jack's motivation for instigating the Tragedy was to merge the world with the Abyss and be reunited with Lacie, who was the younger sister of the previous Glen (originally known as Oswald), as well as Alice and the Intention of the Abyss's mother. Gilbert is also revealed to be a Baskerville who was originally chosen to be the next Glen a century ago. Following this revelation, Oz learns that he is actually the real B-Rabbit and used to be a sentient but still lifeless black rabbit doll that belonged to Lacie until she left him in the care of the Core of the Abyss, of whom gave him life. During the Tragedy of Sablier, Oz was turned into the most powerful Chain in existence, capable of destroying the world, by the Intention of the Abyss in order to help Jack fulfill his goal of plunging the entire world into the Abyss. Meanwhile, Oswald takes over Leo's body and decides to go back into the past to kill Lacie before she met Jack, which would prevent the birth of the Intention of the Abyss, Oz, and Jack's complete slippage of sanity following Lacie's death, thus averting the Tragedy.
Accepting his real origin, Oz decides to prevent Oswald from changing the past with the help of his friends. They come up with a plan to stop the world from falling into the Abyss without changing the past by destroying the Intention of the Abyss' body. Oz's uncle Oscar Vessalius dies on their quest, as well as Break. Traveling back one hundred years into the past during the Tragedy, Alice tries to convince the Core of the Abyss to cut her ties with her twin sister while Oz tries to convince Oswald to reconsider altering the past and focus on helping them stop Jack instead. Alice's words causes the Core to go berserk out of fear of being left alone, which results with the dimensions distorting even more and Oz and the rest being sent further back into the past, before Oswald and Lacie became Baskervilles. In the end, Oswald can't bring himself to kill his sister and passes on, returning control to Leo. Using Oz's illegal contractor seal, they reach the Core of the Abyss and manage to convince the Core to cut her ties with the Intention of the Abyss and restore the world back to normal. Oz and Alice pass away with hopeful dispositions to ensure the safety and security of the world, Gilbert promising them that he will wait for them until they are reincarnated and he can see them again. After the incident, Pandora is disbanded, the Baskervilles establish a new bond with the Core of the Abyss, and Sharon and the rest who have survived move on with their lives. Approximately a century later, Vincent brings the reincarnated Oz and Alice to Gilbert before dying in his brother's arms. Gilbert and Oz both begin crying upon seeing each other for the first time in a hundred years, and Gilbert happily welcomes him and Alice back.
