Kamen Rider Kiva - 46

"Full Stop: Farewell, Otoya"
In 1986, after seeing his father hurt, Wataru battles the Bat Fangire as Kiva and loses to him. Enraged, Otoya uses the Ixa System to take on the King. After his father loses as Ixa and the Ixa Knuckle ends up in the river, Wataru continues the fight until Otoya becomes Dark Kiva despite Wataru and Maya's pleas. The two Kivas battle the Bat Fangire together with a terrified Maya watching. At first the King has the upper hand of the Kivas. But after realizing his father's passion and embracing his father's idealogy, Wataru and his father defeat the King with a double Rider Kick.