Once upon a time, the land was engulfed in complete darkness. The King of Light, who lived in Heaven, wanted to create a nation of light on the land. He sent out his royal son, Rain of the Rainbow to the King of Darkness, Ebb. The two instantly fell in love and did the opposite of what the King of Light wanted: began to live happily in the Kingdom of Darkness.

But one day, Rain suddenly goes missing…?!