Six months prior to the start of the series, a mysterious ritual held on the day of the solar eclipse took place. Its purpose was to give birth to a group of magical creatures called Phantoms through humans with magical potential called "Gates", by forcibly subjecting them to immense despair. Haruto Soma, the survivor of the ritual, and Koyomi, a mysterious girl who has lost all of her memories, are tasked by the mysterious White Wizard to fight the Phantoms. Haruto is also given the Wizardriver to become Kamen Rider Wizard in order to prevent the Phantoms from transforming other Gates into Phantoms themselves. Later on, a man named Kosuke Nito appears as the ancient wizard Kamen Rider Beast to feed on the Phantom's magical power to survive and becomes both a rival and ally to Haruto. As the two wizards wage their battle against the Phantoms, who are led by the hotheaded Phoenix, the cold and merciless Medusa, the scheming Gremlin, and the enigmatic Wiseman, things are not all as they seem.