Jiro was brought to his foster parents by a gigantic oni when he was a baby. The oni promised to return after fifteen years to reclaim Jiro. When his appointed time arrived, Jiro was faced with the challenge of defending his loved ones from enemy oni, malevolent cultists, and their henchmen. He had to embark on a perilous quest through time, space, and alternate dimensions to fulfill his destiny as the reincarnated Shuten Doji.