With You: Final Transformation

With You: Final Transformation (ウィズユー・最後の変身) is the forty-fifth episode of Kamen Rider Kiva.

Plot
In 1986, during their brief encounter with Dark Kiva, Otoya is rescued by Wataru from the grips of King, only to invoke his wrath and reveal his true form as the Bat Fangire. Escaping the monster and later Wataru, Otoya encounters Kivat-bat the 2nd who delivers a message from Maya telling them they cannot meet again. She reveals that the King is using their son Taiga as leverage against her, vowing to kill the baby if she ever comes in contact with Otoya again. In light of his nemesis' cruel methods, Otoya offers to rescue Taiga; an equally disgusted Kivat-bat the 2nd proposes to enter a pact with him that would allow Otoya to use the power of Kiva, even though it would endanger the man's life. Wataru, who overhears the discussion, is requested by Maya to save Taiga; however, Otoya refuses to let Wataru something he wants to do. Overwhelmed by the situation, Wataru excuses himself only to encounter King, escalating into full-blown combat between the two Kivas, until Otoya arrives. The situation soon turns dire as Wataru is injured intercepting an attack meant for his father. Facing imminent danger, Otoya enters the pact with Kivat-bat the 2nd and becomes Dark Kiva and forces the King to retreat. With the Bat Fangire gone, Otoya is left to brave the pains of his pact, knocking Wataru unconscious. Found by Yuri, she offers advice to Wataru not to continue his plan as it would mean Mio would never know him. Finding Maya, Wataru learns that Otoya is making a rescue attempt to Castle Doran to save the Arms Monsters and Taiga. Once inside Castle Doran, Otoya manages to free the Arms Monsters, but he is discovered by King. Narrowly escaping, Wataru meets with Otoya in the manor's halls and is told the only way to honor Mio is to live a strong life for her. When the King finds them, Otoya covers for Wataru to find Taiga as he transforms into Dark Kiva to fight the Bat Fangire, freeing the Arms Monsters in the process. The Bat Fangire summons a red Sabbat to control Castle Doran, but Wataru assumes Emperor Form to free the dragon from the creature. Meanwhile, the battle between Otoya and the Bat Fangire reaches its climax as Otoya collapses from the strain of Kiva's power.

In 2008, Taiga agonizes over his loss of Mio, with the Bishop only offering harsh words about his King's treasonous fiancée’s actions against their race, before revealing himself as Mio's true executioner and had allowed Wataru to take the blame so he would be too distraught to interfere in their affairs again. However, in spite of the Bishop's confidence that their kind would be unchallenged, Taiga turns his wrath towards him in a violent rage from which the Bishop barely escapes with his life. This act angers the Bishop as he starts attacking human to gather the necessary life energy to exact his revenge against Taiga for his unkingly behavior, only to be interrupted by Nago as he assumes Rising Ixa to stop the Swallowtail Fangire.