Complex sentence: Yuya's father, Yusho Sakaki, disappeared three years ago when he was scheduled for a Duel against the Action Duel Champion and was deemed as a coward who ran away.
Split into simpler sentences: Yuya's father, Yusho Sakaki, disappeared three years ago when he was scheduled for a Duel against the Action Duel Champion. Yusho was deemed as a coward who ran away.