Rio Kastle, known as Rio Kamishiro (神代（かみしろ）璃緒（りお）, Kamishiro Rio) in the Japanese version, is one of the main characters, appearing in the Yu-Gi-Oh! ZEXAL anime. She is the younger twin sister of Shark. Rio is later revealed to be Marin (Merag (メラグ, Meragu) in the Japanese version), a member of the Seven Barian Emperors, who became determined to follow her brother no matter what happened to them and sided with the Barian World. She was absorbed by Vector after losing a Duel to him. She was later revived after Yuma and Astral's Duel.