The year is 2022, the Earth is still under the threat of global warming and environmental deterioration. In order to combat this threat, Japan looks to its past and rediscovers the ancient arts of Ninjitsu. This allows society to create and manipulate the elements in ways that don't harm the environment. Thus, the Diet passed the Ninja Act, stating that all citizens are required to learn ninja training and use jutsu skills to protect the environment and turns Japan into a "ninja society". However, an evil criminal ninja clan called the Niji no Hebi is secretly behind this plan for sinister purposes, as they engange in activity all over the world. Only Rentaro can stop them as the Heart of the Blade... Kamen Rider Shinobi!