I own neither Kamen Rider Kiva, nor The Devil Works Part-Timer!
(The scene opens up, showing ancient map being roll open. On it are five islands that forms a cross.) "Long time ago, in a world filled with magic and miricles, there was a place that consists of five islands, forming a cross. It was called Ente Isla, and for a time, it was a land of endless peace. (The scene shows small villages and markets, the citizens looking happy, and showing a small red headed girl, enjoying her time with her father.) "But all that change when the Demon King Satan and his army attack the human world for a dream of the same peace and prosperity for all beings of darkness." (The scene change, showing a giant leading a large army of monsters. And behind them is a large Gothic castle, and inside it is a menacing being, with red predatory eyes, and dragonic horns on his temple.) "And for a time, he was succeeding his dream." (A village girl screams as she was slain by a goblin soldier, a army of knight are destroyed by a Lich. And archers, that was taking down the Demon King's griffon army, are ambushed by a pack of Wargs, slaying them with ease.) "But that change when a lone hero rose up, and with the blessings of heaven, lead the humans to victory, but not a complete victory." (The demon castle is in fire and ruin as the two armies clash at one another, and bursting through the ruins is the demon king himself, his dragonic wing spread open, with a aura of malice around him.)
"Hear me Humans!" Demon King Satan screams, grabbing everyone's attention. "I shall leave Ente Isla in your hands today, but know this: I shall return! To reclaim and subjugate it for all that live in the dark!"
"And with a wave of his hand, all of the survivors of his army returns to the netherworld, and with another, tore open a hole of great unknown and fled into it, with the last of his general, and the hero in close pursuit." (Demon King Satan falls back into the dark portal, with his general following him soon enough. When the portal is about the close, the hero jumps in, not letting the Demon King escape.) "A month has past, and many wonder what happen to the Demon King. Some say the hero slain the Demon King, at the cost of the hero's life, while others say that the Demon King was locked away, forever banished from Ente Isla. Whatever people say, it is nothing but rumor, but if one thing is true, the Demon King didn't left his throne without a heir. For while a month has past in our world, nearly two decades has pass in the world the Demon King now resides." (The scene changes from Ente Isla, to Tokyo, Japan, showing a young teenager, looking at a slash mark that is visible on a church's door. As the teen leaves, he is showing that he is wearing heavy clothing, a medical mask, safety goggles, and a scarf, but that's not the most striking thing about him, for he has black hair, and red predatory eyes, just like his predecessor.)
[Kamen Rider Kiva- Break The Chain]
From the creator that brought you Those Obnoxious Demons, bring you another tale to the Kamen Rider fandom. A tale that will be written in the past and present. (A split screen appears, showing on the left side to be Sadao Mao, former Demon King Satan, dressed as a musician, with 1983 behind him. And on the right is his son, Sadao Mao the Second. While appearing a bit more feminine, still appears just like a exact replica of his father, dress like a MgRonold worker, with the year 2000 in the background.)
While the original Demon King tries to survive the human world in the past, his son tries to find his place in the world in the present, while facing his destiny. (The former Demon King tries to put his new musical talent to earn money from pass buyers. While in the year 2000, Sadao is working in the MgRonold, trying to give good service, but hears a violin hum in the distance, quickly making a excuse to leave, earning a look of worry from a young girl. As he runs, a small bat flies to him) "Yosh, lets go, Sadao!"
"Right, Kivat." Sadao said as he continues running to the warehouse district. (As he was running toward the district, a red headed woman is struggling to stands as she is being continually being beaten by a blue horse monster that appears to made of stain-glass. As the monster was about to strike, he sense something and turning around. The woman stands up and then sees what the monster's sees, her face full of shock and hate.)
A Destiny that is forged in the past. (Sadao was walking towards the group, with Kivat Bat the Third flying around him.) "Kivat!"
"Yosh! Lets do this!" Kivat flies into Sadao's open hand, and opens his mouth. "GABUU!"
A destiny he must face as... (Sadao place Kivat on his opposite hand, let him to bite him. Soon stain-glass tribal marking begin to appear on his face, while chains appear, wrapping around his waist.) "HENSHIN!" (He soon place Kivat on the belt, releasing a mercury like metal all over him, quickly forming a vampiric like armor. It then shatters to reveal the armor's true appearance.) KIVA!
Uncover Satan's past, his friends and foes, (Behind Satan are a trio of monster that look like classic monsters, while Satan is facing shadows of four high class chess pieces.) while Sadao face the present with help of friends, to face his father's enemies. (Beside Sadao, beside the girl he works with, are monsters similar to the one behind Satan, but they appear younger, and two of them appear to be girls. Soon dark shadows appear, not only the same Shadows Satan faced, but also outlines of demonic and holy people.)
Sadao the Second must have the strength to find his place and face his destiny for he is...
The Part time Kamen Rider!
(Not long, Kiva is walking away, but soon faces the red haired woman, her face still full of scorn and hate.) "So, I finally found you..." The red haired woman said, as she pulls out a chain dagger from her pocket. "Demon King SATAN!" She charges at Kiva and the scene froze, with chains bursting out.
Here are this Story's main story points:
Satan replaces Otoya Kurenai, and Wataru's name changes to Sadao Maou the Second.
While Satan interacts in the 80s part of the Kiva-verse, Sadao is facing the Fangires, the Checkmate Four, Emilia, and the foes from Ente Isla.
While Satan interacts with Jiro, Ramon, and Riki, Sadao will be aided by different Wolfen, Merman, and Franken, two of which will be female. Their relationship with Sadao is up to you.
Sadao and Chiho are childhood friends, and Sadao somewhat aware of Chiho's feelings for him, you decide how far their relationship will go as the story progress.
And of course those from Ente Isla will initially mistakes Sadao for his father, Satan.