Rio Kamishiro

Ryoga's younger twin sister. Rio once dueled IV who was operating under the orders of Tron. He played a card, "Flaming Hell Blessing", that set the surrounding area on fire. She was critically injured in the blaze and remained in the hospital for the entire first series. After the incident, Ryoga swore to avenge his younger sister, aiming his hatred towards IV. She recovers in the second series and is able to return to school again. Rio stays strong and prefers to defend herself for her brother Ryoga, fearing his many enemies will use her to get to him. She is a confident and adamant person, getting annoyed when things do not go her way. She is also a skilled duelist who uses an ice-themed deck.

Despite all of this, Rio is extremely frightened of cats. (Source: Yu-Gi-Oh Wikia)