Age: 6 (18 in 1998)
Brother: Ushiromiya Battler
Mother: Ushiromiya (Sumadera) Kyrie
Father: Ushiromiya Rudolf
Best Friend: Mammon
First Apparition: Banquet of the Golden Witch (EP3)
Seiyuu: Rina Sato
She Loves: Battler onii-chan, Maria nee-chan, eating, reading, gifting a lot of money to the poors.
She Hates: The rest of the world, her life, be alone.
Quote: "Dameda, zenzen dameda ( 駄目だ、全然駄目だ )" (It's useless, It's all useless)
ABOUT EPISODE 6 OF THE GAME
Ange is introducted at the end of the Episode 3: Banquet of the Golden Witch, and since she's daughter of Rudolph and Kyrie, she could be considered Battler's half-sister.
In the development of the story it's revelated that Battler isn't son of Ushiromiya Asumu, his dead mother, and in the Episode 6: Dawn the Golden Witch, we find the truth: Battler is son of Kyrie. So Ange is his real younger sister, even if we already understood this because of Ange and Battler's appearences, they share same peculiarities (even the same quotes).
She could not come to the island in 1986 due to a sickness. After the events of Banquet of the Golden Witch , she is raised by Eva after she returns alive from Rokkenjima, and studies to become the next family head. However, she is put through many hardships particularly due to Eva's belief that her son George should have been the next head. Before her death in 1998, Eva passes down the name of "Beatrice" to Ange, who becomes the new Endless Witch. Ange attempts to commit suicide by jumping off a building so she can be with her family, but is stopped by the witch Bernkastel, who offers to help Ange solve the mysteries on Rokkenjima. Despite being the last witch of her time period, Ange, like Battler, does not believe in witches. However, she does understand witches along with their strengths and weaknesses, making her denial of witches very dangerous to them. Like her brother, she has a habit of saying, "It's useless, it's all useless" during difficult situations. Although she was seemingly ripped to pieces in Alliance of the Golden Witch , she is alive and well in the world of 1998, and seeks to continue searching for the truth with help from the witch Featherinne Augustus Aurora.
Ange-Beatrice is the witch form of Ange Ushiromiya, and one of the successors to the name "Beatrice." She inherited the titles of Golden and Endless Witch from Eva on her deathbed in the year 1998 following the events of Banquet of the Golden Witch and, with Bernkastel's blessing, is the last witch of her time period. Like her brother Battler, she denies witches and has a strong magical resistance. However, she also accepts the possibility that magic and witches exist, which allows her to use magic and summon furniture, particularly the Seven Stakes of Purgatory, making her a formidable threat to witches and other magical beings. She also awakens as the Witch of Resurrection , allowing her to resurrect humans and furniture using any vessel. She uses her Magic of Resurrection once when she comes across the torn remains of Sakutaro, Maria's beloved stuffed animal and furniture who was made and ultimately destroyed by Rosa, and uses it to bring Sakutaro back to life before Maria, a feat Beatrice was ultimately unable to do. Ange becomes Battler's ally in the meta-world throughout Alliance of the Golden Witch , hoping to expose the truth on the Rokkenjima murders and free her family from Beatrice's clutches. She is forbidden to reveal her identity as Battler's sister to him, however, prompting her to utilize the alias Gretel (jokingly suggested by Battler to be a possible reference to the fairy tale Hansel and Gretel ). She and Battler both acknowledge that she isn't to be granted too much trust as an ally, considering how Beatrice manipulated and deceived Battler in Banquet of the Golden Witch . As a result, Ange participates in Battler and Beatrice's game as a third party, observing the other two from afar and providing tips to Battler regarding how to solve the mystery, all the while allowing Battler to consider whether or not to follow those tips. She is also responsible for the change in the flow of the game, leading to Battler being granted the ability to use the blue truth against Beatrice's red truth. However, it is revealed by Lambdadelta that Ange is no more than another piece Bernkastel threw into the game to prevent Beatrice from winning, and that if she were to succeed in saving her family, they would return to her past self in 1986 and not her current self in 1998. When Beatrice loses interest in the game and abandons it by deeming Battler unqualified to be Kinzo's grandson and thus her opponent, causing Battler to question his own identity and fade from existence, Ange intervenes by overruling Beatrice's theory of Battler's lineage, which gradually begins to restore Battler. However, it is only until Ange reveals her identity to him that she is able to completely revive him. Having violated the rule of keeping her identity a secret, Ange is violently torn to pieces and killed. Her death ultimately motivates Battler into winning the game and freeing his family throughout the rest of the series.
Some of these informations are from Wikipedia