Diamond Queen

Joker and Spade's childhood rival and friend. Queen is a strong-willed young girl that won't let anyone get in her way to steal something, although she sometimes shows her sensibility. Although she is very attached and loyal to Silver Heart, she won't hesitate to tell him off when he does something unreasonable. Though beautiful and cute, she is very tough.

Queen is portrayed as physically powerful, relying on her brains and muscle more often than gadgets, unlike her rival phantom thieves. Queen is skilled with her diamond sword, which can cut through nearly anything.

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Queen is the heir of the kingdom of Emerald, born as Queen Emerald. When she was a baby, her parents died in a fire, but not before entrusting her to Silver Heart, who had initially been planning to steal a treasure from the kingdom. However, because he valued life as the ultimate treasure, he gave up on stealing and took her in instead. To keep her safe, Silver Heart changed her name to Diamond Queen. After discovering her true origins, Queen ran away from home and disassociated herself from phantom thieves and Silver Heart, opposing them. In the anime, she was manipulated by Professor Clover to join his organization and was given a false backstory for what had really happened to her, assuming that Silver Heart had killed her parents, when in reality it had been someone else.