Yudai is a 14 year old Duel Monsters player who wants to become a pro. He lives in Neostar city, and is friends with the timid Kieran, fiery Marina, the snarky cowboy Rider, and Rider's puppy Beckett. He loves dueling a lot. He is very quick to help others in need. He is very competitive, even beyond dueling. He doesn’t let a loss discourage him. His ace monster is Kaleido Chimera. Yudai is kind to anyone he meets, but doesn't take disrespect. He has a 6-year-old sister named Yua.