Dalian is the Black Yomihime (読姫?, literally "reading princess") and is the custodian of the Bibliotheca Mystica de Dantalian housing 900,666 phantom books. Her Keykeeper is Huey.
She is what many people call a tsundere. While she is mostly rude, mean and calls people names,(especially to Huey)she gets very clingy and jealous when Huey is near another woman. She also blushes sometimes when she's with Huey or when she gets embarrased. Her only shown weakness is sweets especially scones with tea, which Camilla uses to bribe her with.
Dalian looks way younger than her actual age, she may be hundreds of years old. As seen in episode 5, she says that she didn't expect someone like a magician in this day and age and the fact that most of the characters know her, even if she's never seen them before. She wears a tiara and a black dress and is usually seen reading a book.
She is first seen asking Huey what he was doing at the mansion after he mistook her for a doll. After he tells her that he has to inherit the mansion and the library, she looked shocked at this. She became angry when he thought that the name "Dalian" from the letter was a pet name and kicked Huey, telling him Dalian was her name. In the kitchen, she asks Huey if she was a soldier but he replies saying that he was just a pilot. Dalian states that Wesley was a fine human and Huey is relieved, saying he wasn't completely alone. Dalian smells a bun in his coat and asked for some sugar to eat it with and they sit down to talk about the library. Dalian begins to explain the Phantom Books and that they didn't belong in the world but Huey just laughs, saying that it was an interesting story. Dalian gets mad at this but notices that he has the Key and asks where he got it. However, they are interupted by the arival of Huey's escort and they make their way to Mr.Conrad's mansion. On the way there she explains the proof that he was the one who killed Wesley. They arrive and soon after they find the escort dead and a knife thrower but Huey dodges and takes out his gun. Dalian is shocked that he carries a gun and Huey shoots it and it quickly turns to dust and this happens again when they meet a lion. She warns that there may be snakes of clowns around and tells him more about the Phantom Books. A dragon suddenly appears and attacks them. Huey tells Dalian to hurry to the study since she knows how to seal the Phantom Books while he distracts it. She is shocked at this but tells him to take out the key and read the pledge and he does so. Huey takes the key and turns the lock on her chest, opening a hole and he pushes his hand inside her and takes out a Phantom Book. He then reads it, destroying the dragon and they make their way to the study. After they seal the Phantom Book, Dalian says she's hungry and they walk outside. Huey holds his hand infront of her and Dalian says that she has no choice but to go with him.