Ryuusei Onise is a fictional character from the popular Japanese manga and anime series Yu-Gi-Oh!. He is known for his role as a skilled duelist and a member of the Doma organization, which seeks to capture powerful duelists. Ryuusei is characterized by his unique abilities and his determination to prove himself in the world of card games. In the series, Ryuusei uses a deck that features Dragon monsters, showcasing his strategic skills in battles. His interactions with other characters, including Yugi Muto and Seto Kaiba, highlight the themes of friendship and rivalry that are central to the Yu-Gi-Oh! franchise.