Rio Kastle

Rio Kastle, known as Rio Kamishiro in the Japanese version, is a character appearing in the Yu-Gi-Oh! ZEXAL anime. She is the younger twin sister of Shark.

Appearance
Rio has dark red eyes, and like her brother, she has pale skin and dark purple hair with light blue bangs. Rio also wears a ring on her right little finger which was previously owned by her brother.

Her attire includes a white jacket over a light purple shirt, black stockings and white high heeled shoes. At school, she wears a green female uniform.

Personality
Despite her appearance and previously spending a large amount of time in hospital, she is a confident and adamant person, getting annoyed when things do not go her way. This is usually shown when conversing with her brother. Her confident personality assists in her interests, allowing her to conquer sports such as soccer, basketball, and boxing with relative ease. Despite all of this, Rio is extremely frightened of cats.

Rio tends to be annoyed when people refer to her as Shark's sister instead of calling by her name. This further seen many times during her duel against Aika as she got mad her or much towards Yuma as he kept calling her like that.

History
As children, Rio and her brother Reginald were visiting a theme park where she offered Reginald one of two rings which they both could wear. Reginald initially refused to wear it causing Rio to throw them on the ground and walk away in anger.

Rio once Dueled Quattro who was operating under the orders of Vetrix. He played a card, "Flaming Hell Blessing", that set the surrounding area on fire. She was critically injured in the blaze, though Quattro carried her to safety, his face being scarred in the process. After this, Reginald began wearing both of the rings from their childhood to remind himself of her.

In order to help his sister, Shark entered the National Duel Circuit and made it to the final match against Quattro. In the break room, Quattro set his Deck up to fall on the floor, causing Reginald to see some of its contents. This caused him to be disqualified.

Yu-Gi-Oh! ZEXAL II
Even after the World Duel Carnival, Rio was still in the hospital, albeit with only bandages covering her eyes. For some reason Rio felt Gilag's arrival from the Barian World which caused her pain. Because of this, Reginald (who by now often used "Shark" as a nickname) arrived later along with Yuma and Tori after him being called by the hospital as well as sensing Rio's pain. During that time Rio blurted out that someone is coming to take the most important thing, which worries Yuma as he knew what Rio was talking about.

Shark visited Rio at hospital again and gives her one of his rings which were given to him by her when they were younger. She was later abducted by Sentaro Ariga following Gilag's orders and is imprisoned in a cage.Sentaro approached Shark and informed him of this, causing them to Duel. When Shark attempted to use "Zeus Breath", Sentaro threatened to harm Rio if he activated it. Yuma and Rei Shingetsu go to Sentaro's manga writing room and manage to find several pages detailing how the Duel would go, as well as the result, which resulted in the death of both siblings. However, Shark called out to her and their bond manages to shatter her imprisonment, making her appear on top of a tower on the "Comic Field" Field Spell Card. When her bandages are blown off of her face, she insulted Shark's Dueling skills. After the Duel, she collapses and is carried away by Shark.

Deck
Rio plays a Ice-themed Deck featuring WATER Winged Beast-Type monsters.