About 25 years ago ─── The story before the birth of Igarashi brothers and sisters. A dying and seriously injured man was brought to the scientific research organization Noah. The man ── Junpei Shiranami was transplanted with Giff's cells into the heart by Masumi Karizaki and survived. He is then forced to become the strongest demon hunter and given a bail driver. Junpei, whose parents were killed by the red devil, becomes a Kamen Rider Vail with his revenge in mind and continues to fight the devil.