Celestia Ludenberg

Celestia Ludenberg (セレスティア・ルーデンベルク) a  student in  Gothic Lolita costume who is a famous gambler and known as the "Queen of Liars." Her title is  Super High School Level Gambler (超高校級の「ギャンブラー」) . Her real name is Taeko Yasuhiro.

Personality
An experienced gambler, Celestia appears collected and cunning in nature. She possesses the ability to manipulate others into her bidding and can lie with a straight face, granting her the title of "[the] Queen of Liars". She makes use of these abilities by tricking Yamada into killing Ishimaru and deceiving the other students for the most part of Chapter 3.

Celestia is shown to be fairly intelligent, referencing several aspects of game theory such as Prisonner's Dilemma or Zero Sum Game, and her short-temperedness surfaces when something fails to go as well as she expects it to.

Pre-Despair Incident
Little is known about Celestia's life prior to being trapped within Hope's Peak Academy. However, from Naegi's interactions with her during Free Time periods, one can discover that Celestia has been gambling for the most part of her life, and that she has not heard the term "lose" for a long while. She also reveals that she used to visit a cafe (with an owner that somewhat resembled Yamada), where she would enjoy her preferred Royal milk tea.

High School Life of Mutual Killing
Much like the other students, Celestia awakens to find herself trapped inside the school grounds, to her annoyance. She appears to adapt quickly to the new conditions, claiming that it is the only way to survive, and suggests the others do the same.

When Monobear introduces the first "motive" to each of the students through individualised footage on CDs, Celestia is horrified at what her CD shows (but refuses to say what exactly she saw, which is never revealed). She aids the students in solving the first case after the deaths of Maizono and Mukuro (disguised as Enoshima).

Celestia plays a key part in Chapter 2, having encountered Fujisaki in the storage room prior the latter's death. During this encounter, Celestia notices Fujisaki's blue jersey partially hanging out from his bag, which he then stuffs back inside before going off in a hurry. This later proves to be a major factor in figuring out who murdered Fujisaki.

In Chapter 3, Celestia plans to commit a murder herself. She takes Alter Ego, the AI developed by Fujisaki before his death, and hides it to cause confusion and upset both Yamada and Ishimaru. Later, she enlists Yamada as her accomplice (and tells him that she will act as his) by saying that Ishimaru took Alter Ego, and that he plans to kill him [Yamada]. Yamada believes her and the two begin to conspire. They frame Hagakure by knocking him out and stuffing him into a robot suit. Celestia organises Yamada's "death" after Ishimaru is killed, managing to trick the others into looking for the suspicious person wearing a robot suit. After Yamada relocates himself and Ishimaru's body to the Art Room, Celestia turns against and kills him, as she planned to do from the beginning.

During the school trial, Celestia urges the students to declare Hagakure the culprit. However, Togami, Naegi, and Kirigiri see past her lies and manage to prove Hagakure's innocence. They continuously push Celestia until she finally breaks and "loses" the trial. She admits to her crimes and is prepared to face her execution, stating that she wants to go out "gracefully". She gives Kirigiri the key to the locker Alter Ego is stashed in, bidding her classmates farewell and having Monobear drag her off to her death afterwards.

Execution
Versailles Witch Hunt Style - Celes is meant to be burnt at the stake, the kind of romanticised, gothic death she would be (and is) content with. However, a fire truck appears and crashes into her, ending her execution in an ironic fashion.

Trivia

 * It is revealed that Celestia's dream is to own and live in a castle, with a large number of servants (all dressed as vampires) waiting on her. It is unknown, however, whether this is another lie of hers or otherwise.
 * Celestia admits that once she managed to accumulate over ten billion yen through gambling.