Kamen Rider Series S31E01 - はじめに、炎の剣士あり

Novelist and bookstore owner Touma Kamiyama suffers a recurring dream about a place called Wonder World invading the real world and his inability to save a mysterious young girl 15 years prior. His dreams become reality when he is dragged into a war to decide the fate of both worlds, so he takes matters into his own hands when he obtains the means to transform into Kamen Rider Saber.